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Effects of Irrigation Volumes and Frequencies on the Growth, Yield and Postharvest Quality of Winter Strawberries Grown ...

Permanent Link: http://ufdc.ufl.edu/UFE0041944/00001

Material Information

Title: Effects of Irrigation Volumes and Frequencies on the Growth, Yield and Postharvest Quality of Winter Strawberries Grown on Sandy Soils
Physical Description: 1 online resource (128 p.)
Language: english
Creator: Ramirez-Sanchez, Mari
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: frequency, irrigation, postharvest, sandy, soils, strawberry, volume, yield
Horticultural Science -- Dissertations, Academic -- UF
Genre: Horticultural Science thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Florida is the second largest strawberry producing state in the U.S. with a planted area of more than 3,000 ha. Strawberry production has a high water requirement for crop establishment, growth, and freeze protection. Florida strawberry growers use a wide range of irrigation programs to grow the crop. Contamination of ground water resources has profound environmental implications that make necessary the regulation and conservation of this resource. The objective of this study was to compare plant growth, fruit yield and postharvest quality of strawberry cultivars under various drip irrigation volumes and frequencies. The irrigation volumes were 1.8, 3.6 and 5.4 L/m/day and the two frequencies were one and two cycles per day and they were tested during the 2008-09 and 2009-10 strawberry seasons. Strawberry plant diameter and foliar nutrient content were determined at 6, 12 and 18 weeks after transplanting, root and shoot dry weight at the end of the season and marketable fruit through 24 harvests per season. Fruits were collected from each plot to determine total titratable acidity and soluble solids content of each treatment at harvest. All nutrients were in adequate range for all irrigation programs through both seasons. Early yield of ?Strawberry Festival? during the first season was not affected by irrigation programs, ranging between 7.8 and 9.0 t/ha. The lowest total yield was found in plots irrigated twice per day with 1.8 L/m/day, whereas the highest fruit yields were obtained in plots irrigated with either 3.6 or 5.4 L/m/day in one or two cycles, but with better results when irrigated in two cycles per day, ranging between 29.6 and 30.0 t/ha. Higher water volume resulted in higher ?Strawberry Festival? plant diameter and shoot dry weight. Total titratable acidity was higher at 22 weeks after transplant for the irrigation volume of 1.8 L/m/day. In the second season there was a cultivar effect for both early and total yield. The highest early yield was obtained by ?Florida Radiance?, and ?Winter Dawn? had the highest total yield of 13.40 ton/ha. ?Winter Dawn? had the highest root dry weight. There were no effects on total titratable acidity and soluble solids content among irrigation programs. ?Winter Dawn? had the highest total titratable acidity and the lowest soluble solids content in most evaluations. The results showed that reducing irrigation volumes from 5.4 L/m/day over a period of 24 weeks to 1.8 L/m/day at a frequency of twice a day for the first eight weeks and then 3.6 L/m/day at a frequency of twice a day for the remaining 16 weeks could save an estimated of 11 million m3 of water per 24-week season for the Florida strawberry industry as a whole. The suggested irrigation volumes and frequencies can be used without causing plant stress, reducing yield and compromising postharvest quality.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Mari Ramirez-Sanchez.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Santos, Bielinski M.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0041944:00001

Permanent Link: http://ufdc.ufl.edu/UFE0041944/00001

Material Information

Title: Effects of Irrigation Volumes and Frequencies on the Growth, Yield and Postharvest Quality of Winter Strawberries Grown on Sandy Soils
Physical Description: 1 online resource (128 p.)
Language: english
Creator: Ramirez-Sanchez, Mari
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2010

Subjects

Subjects / Keywords: frequency, irrigation, postharvest, sandy, soils, strawberry, volume, yield
Horticultural Science -- Dissertations, Academic -- UF
Genre: Horticultural Science thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Florida is the second largest strawberry producing state in the U.S. with a planted area of more than 3,000 ha. Strawberry production has a high water requirement for crop establishment, growth, and freeze protection. Florida strawberry growers use a wide range of irrigation programs to grow the crop. Contamination of ground water resources has profound environmental implications that make necessary the regulation and conservation of this resource. The objective of this study was to compare plant growth, fruit yield and postharvest quality of strawberry cultivars under various drip irrigation volumes and frequencies. The irrigation volumes were 1.8, 3.6 and 5.4 L/m/day and the two frequencies were one and two cycles per day and they were tested during the 2008-09 and 2009-10 strawberry seasons. Strawberry plant diameter and foliar nutrient content were determined at 6, 12 and 18 weeks after transplanting, root and shoot dry weight at the end of the season and marketable fruit through 24 harvests per season. Fruits were collected from each plot to determine total titratable acidity and soluble solids content of each treatment at harvest. All nutrients were in adequate range for all irrigation programs through both seasons. Early yield of ?Strawberry Festival? during the first season was not affected by irrigation programs, ranging between 7.8 and 9.0 t/ha. The lowest total yield was found in plots irrigated twice per day with 1.8 L/m/day, whereas the highest fruit yields were obtained in plots irrigated with either 3.6 or 5.4 L/m/day in one or two cycles, but with better results when irrigated in two cycles per day, ranging between 29.6 and 30.0 t/ha. Higher water volume resulted in higher ?Strawberry Festival? plant diameter and shoot dry weight. Total titratable acidity was higher at 22 weeks after transplant for the irrigation volume of 1.8 L/m/day. In the second season there was a cultivar effect for both early and total yield. The highest early yield was obtained by ?Florida Radiance?, and ?Winter Dawn? had the highest total yield of 13.40 ton/ha. ?Winter Dawn? had the highest root dry weight. There were no effects on total titratable acidity and soluble solids content among irrigation programs. ?Winter Dawn? had the highest total titratable acidity and the lowest soluble solids content in most evaluations. The results showed that reducing irrigation volumes from 5.4 L/m/day over a period of 24 weeks to 1.8 L/m/day at a frequency of twice a day for the first eight weeks and then 3.6 L/m/day at a frequency of twice a day for the remaining 16 weeks could save an estimated of 11 million m3 of water per 24-week season for the Florida strawberry industry as a whole. The suggested irrigation volumes and frequencies can be used without causing plant stress, reducing yield and compromising postharvest quality.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Mari Ramirez-Sanchez.
Thesis: Thesis (M.S.)--University of Florida, 2010.
Local: Adviser: Santos, Bielinski M.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2010
System ID: UFE0041944:00001


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EFFECTS OF IRRIGATION VOLUMES AND FREQUENCIES ON THE GROWTH,
YIELD AND POSTHARVEST QUALITY OF WINTER STRAWBERRIES GROWN ON
SANDY SOILS


















By

MARICRUZ RAMIREZ-SANCHEZ


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2010

































2010 Maricruz Ramirez-Sanchez




























To Juan and Yolanda









ACKNOWLEDGMENTS

I thank my parents and siblings for all their love and support, as well as my

godfathers and friends for being there constantly. I would like to thank my advisor Dr.

Bielinski Santos for giving me this opportunity and for his words of wisdom. I also would

like to thank the members of my committee Dr. Craig Chandler and Dr. Steven Sargent,

the Horticulture Laboratory staff of the Gulf Coast Research and Education Center and

the Postharvest Laboratory staff of the Horticultural Sciences Department.









TABLE OF CONTENTS

page

ACKNOW LEDGM ENTS .............. ............................ .......................................... 4

LIST O F FIG URES........................................... ............... 10

A BSTRA CT ..................................................................................................... 12

CHAPTER

1 INTRO DUCTIO N ...................... ... ............. ................................. ........... 14

2 LITERATURE REVIEW ........ ........ ......... ............................... 16

Strawberry Postharvest Quality ...... .................. .... ............... 17
Production System ............... .............................. 20
Water Management ......... ........ ......... .... ........................... 21
Im portance of the S tudy ...................................................................... ......... 28

3 EFFECTS OF IRRIGATION VOLUMES AND FREQUENCIES ON THE
GROWTH, YIELD AND POSTHARVEST QUALITY OF 'STRAWBERRY
FESTIVAL' GROWN ON SANDY SOILS, 2008-09 SEASON............................... 30

Materials and Methods................................ ............... 30
Results and Discussion............................. .............. 34
2008-09 Strawberry Season Environmental Conditions ......... ............... 34
Plant Diameter and Chlorophyll Content ........ .......... ................... 34
Root and Shoot Dry W eight................................................. .................... 35
Foliar Nutrient Concentration......................... ...... ......... 35
Pre-storage Strawberry Fruit Quality ................................. .. ..... ......... 37
Post-storage Strawberry Fruit Quality ............. ................... .. .............. 38
Early and Total Yields ......... ........................................................ 39

4 EFFECTS OF IRRIGATION VOLUMES AND FREQUENCIES ON THE
GROWTH, YIELD AND POSTHARVEST QUALITY OF 'STRAWBERRY
FESTIVAL', 'FLORIDA RADIANCE' AND 'WINTER DAWN' ON SANDY SOILS,
2009-10 SEASO N .... ......................................... ............... 70

Materials and Methods................................ ............... 70
R results and D iscussion....................................... ...................................... 74
2009-10 Strawberry Season Environmental Conditions............................... 74
Plant Diameter and Chlorophyll Content ........ ........ ............... .. ............... 74
Root and Shoot Dry W eight............................................ ........................... 75
Foliar Nutrient Concentrations...................... ...... .......................... 75
Pre-storage Strawberry Fruit Quality ................................ ... .................. 78









Post-storage Strawberry Fruit Quality ......... ......... ... ........... ......... 80
Early and Total Yield .............. ................................. 83

5 SUMMARY AND CONCLUSIONS................ ............................ 104

APPENDIX: TEMPERATURE DATA FROM FAWN WEATHER REPORT FOR
BALM, FLORIDA DURING 2008-09 AND 2009-10 STRAWBERRY SEASONS.. 111

LIS T O F R E FE R E N C E S .................................................................................. 12 1

BIO G RA PH ICA L SKETC H .................................................. 128









LIST OF TABLES
Table page

3-1 Average environmental conditions from October 2008 to March 2009 from
FAWN0 weather report for Balm, Florida. ........................... ............... 44

3-2 Effects of irrigation volumes and frequencies on 'Strawberry Festival' plant
diameter and leaf chlorophyll content at 6, 12, and 18 weeks after transplant
(WAT). 2008-09 Season ................................................ 44

3-3 Effects of irrigation volumes and frequencies on 'Strawberry Festival' root
and shoot dry weight at 25 weeks after transplant. 2008-09 Season ................ 45

3-4 Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
nutrient concentration at 6 weeks after transplant. 2008-09 Season ............... 46

3-5 Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
nutrient concentration at 12 weeks after transplant. 2008-09 Season ............ 47

3-6 Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
nutrient concentration at 24 weeks after transplant. 2008-09 Season ............ 48

3-7 Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
quality; pre-storage (8 days at 5C) evaluation at14 weeks after transplant.
2 0 0 8 -0 9 S e a so n ......................................................................... 4 9

3-8 Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
quality; pre-storage (8 days at 5C) evaluation at 18 weeks after transplant.
2008-09 Season. .............. ..... .......................... ..... ....... ........ 50

3-9 Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
quality; pre-storage (8 days at 5C) evaluation at 19 weeks after transplant.
2008-09 Season. ..................................... ................. .... .... ............... 51

3-10 Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
quality pre-storage (8 days at 5C) evaluation at 22 weeks after transplant.
2008-09 Season. ..................................... ................. .... .... ............... 52

3-11 Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
quality post-storage (8 days at 5C) of fruit harvested at 19 weeks after
transplant. 2008-09 Season. ........................................ ......... ............... 53

3-12 Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
quality post-storage (8 days at 5C) evaluation of fruit harvested at 22 weeks
after transplant. 2008-09 Season. .................................... ....................... 54

4-1 Average environmental conditions from October 2009 to March 2010 from
FAWN0 weather report for Balm, Florida. ........................... ............... 87









4-2 Effects of irrigation volumes and frequencies on strawberry plant diameter at
6, 14, and 17 weeks after transplant (WAT). 2009-10 Season. .......................... 88

4-3 Effects of irrigation volumes and frequencies on strawberry leaf chlorophyll
content at 6, 14 and 17 weeks after transplant (WAT). 2008-09 Season. .......... 89

4-4 Effects of irrigation volumes and frequencies on strawberry root dry weight at
22 weeks after transplant. 2009-10 Season. ................. ......... .............. 90

4-5 Effects of irrigation volumes and frequencies on strawberry shoot dry weight
at 22 weeks after transplant. 2009-10 Season. ................................................ 91

4-6 Effects of irrigation volumes and frequencies on strawberry foliar nutrient
concentration at 6 weeks after transplant. 2009-10 Season............................. 92

4-7 Effects of irrigation volumes and frequencies on strawberry foliar nutrient
concentration at 14 weeks after transplant. 2009-10 Season............................. 93

4-8 Effects of irrigation volumes and frequencies on strawberry foliar nutrient
concentration at 17 weeks after transplant. 2009-10 Season............................. 94

4-9 Effects of irrigation volumes and frequencies on strawberry fruit quality pre-
storage (8 days at 7C) evaluation at 14 weeks after transplant. 2009-10
Season. ........................................ ......................... ............... 95

4-10 Effects of irrigation volumes and frequencies on strawberry fruit quality pre-
storage (8 days at 7C) evaluation at 17 weeks after transplant. 2009-10
Season. ........................................ ......................... ............... 96

4-11 Effects of irrigation volumes and frequencies on strawberry fruit quality pre-
storage (8 days at 7C) evaluation at 20 weeks after transplant. 2009-10
Season. ........................................ ......................... ............... 97

4-12 Effects of irrigation volumes and frequencies on strawberry fruit quality post-
storage (8 days at 7C) evaluation at 14 weeks after transplant. 2009-2010
Season. ........................................ ......................... ............... 98

4-13 Effects of irrigation volumes and frequencies on strawberry fruit quality post-
storage (8 days at 7C) evaluation at 17 weeks after transplant. 2009-2010
Season. ........................................ ......................... ............... 99

4-14 Effects of irrigation volumes and frequencies on strawberry chroma post-
storage (8 days at 7C) at 17 weeks after transplant 2009-10 Season............. 100

4-15 Effects of irrigation volumes and frequencies on strawberry fruit quality post-
storage (8 days at 7C) evaluation at 20 weeks after transplant. 2009-2010
Season. ............ ............................................. 101









4-16 Effects of irrigation volumes and frequencies on strawberry early and total
yield. 2009-10 Season ............................................................................... 102

A-1 Daily average of data from FAWN0 weather report taken at 60 cm from soil
from October 2008 to March 2009, Balm, FL. ....................... ..................... 111

A-2 Daily average of data from FAWN0 weather report taken at 60 cm from soil
from October 2009 to March 2010, Balm, FL. ....................... ..................... 116









LIST OF FIGURES


Figure page

3-1 Effects of irrigation volumes and frequencies on 'Strawberry Festival' A)
plant diameter (cm) at 18 weeks after transplant, B) shoot dry weight 25
weeks after transplant. 2008-09 Season. ......................... .............. 55

3-2 Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
nutrient content at 6 weeks after transplant. A) nitrogen (N), B) phosphorus
(P). 2008-09 Season. ............ ......... ..................... ............. ............... 56

3-3 Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 6 weeks after transplant. A) calcium (Ca), B) magnesium (Mg).
2008-09 Season. .............. .... ............ ............. .............. ............... 57

3-4 Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 6 weeks after transplant. A) boron (B), B) iron (Fe). 2008-09
S e a s o n .............. ......... ............................................................... 5 8

3-5 Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 6 weeks after transplant. A) zinc (Zn), B) manganese (Mn). 2008-
09 Season. ............. .... ........... ............................................... 59

3-6 Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 12 weeks after transplant. A) boron (B), B) zinc (Zn). 2008-09
Season. ................................................................ ..... ......... 60

3-7 Effects of irrigation volumes and frequencies on 'Strawberry Festival'
manganese (Mn) foliar content at 12 weeks after transplant. Season 2008-
0 9 ......... .... ..... ................................................ ........................... 6 1

3-8 Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 24 weeks after transplant. A) phosphorus (P), B) calcium (Ca).
2008-09 Season. ....................... .......... .................. ............... 62

3-9 Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 24 weeks after transplant. A) copper (Cu), B) boron (B). 2008-09
S e a s o n .............. ......... ............................................................... 6 3

3-10 Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
firmness (N) pre-storage (8 days at 5C) at 14 weeks after transplant. 2008-
0 9 S e a so n ......................................................................... ..... 6 4

3-11 Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
lightness (L*) pre-storage (8 days at 5C) at 19 weeks after transplant. 2008-
0 9 S e a so n ......................................................................... ..... 6 5









3-12 Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
pre-storage (8 days at 5C) analysis at 22 weeks after transplant. A) total
tritatable acidity (% citric acid), B) lightness (L*). 2008-09 Season..................... 66

3-13 Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
post-storage (8 days at 5C) analysis of fruit harvested at 19 weeks after
transplant. A) total titratable acidity (% citric acid), B) lightness (L*). 2008-09
S e a so n. ........................................................ .. .... ............... 6 7

3-14 Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
post- storage (8 days at 5C) analysis of fruit harvested at 22 weeks after
transplant. A) firmness (N), B) chroma (C*). 2008-09 Season.............. ........... 68

3.15 Effects of irrigation volumes and frequencies on 'Strawberry Festival' early
yield (A) and total yield (B). 2008-2009 Season ................................ .......... 69

4-1 Effects of irrigation volumes and frequencies on soil water content (%). 2009-
10 Strawberry Season .............. ......................... ............... 103









Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

EFFECTS OF IRRIGATION VOLUMES AND FREQUENCIES ON THE GROWTH,
YIELD AND POSTHARVEST QUALITY OF WINTER STRAWBERRIES GROWN ON
SANDY SOILS

By

Maricruz Ramirez-Sanchez

August 2010

Chair: Bielinski M. Santos
Major: Horticultural Science

Florida is the second largest strawberry producing state in the U.S. with a planted

area of more than 3,000 ha. Strawberry production has a high water requirement for

crop establishment, growth, and freeze protection. Florida strawberry growers use a

wide range of irrigation programs to grow the crop. Contamination of ground water

resources has profound environmental implications that make necessary the regulation

and conservation of this resource. The objective of this study was to compare plant

growth, fruit yield and postharvest quality of strawberry cultivars under various drip

irrigation volumes and frequencies. The irrigation volumes were 1.8, 3.6 and 5.4

L/m/day and the two frequencies were one and two cycles per day and they were tested

during the 2008-09 and 2009-10 strawberry seasons.

Strawberry plant diameter and foliar nutrient content were determined at 6, 12 and

18 weeks after transplanting, root and shoot dry weight at the end of the season and

marketable fruit through 24 harvests per season. Fruits were collected from each plot to

determine total titratable acidity and soluble solids content of each treatment at harvest.

All nutrients were in adequate range for all irrigation programs through both seasons.









Early yield of 'Strawberry Festival' during the first season was not affected by irrigation

programs, ranging between 7.8 and 9.0 t/ha. The lowest total yield was found in plots

irrigated twice per day with 1.8 L/m/day, whereas the highest fruit yields were obtained

in plots irrigated with either 3.6 or 5.4 L/m/day in one or two cycles, but with better

results when irrigated in two cycles per day, ranging between 29.6 and 30.0 t/ha. Higher

water volume resulted in higher 'Strawberry Festival' plant diameter and shoot dry

weight. Total titratable acidity was higher at 22 weeks after transplant for the irrigation

volume of 1.8 L/m/day.

In the second season there was a cultivar effect for both early and total yield. The

highest early yield was obtained by 'Florida Radiance', and 'Winter Dawn' had the

highest total yield of 13.40 ton/ha. 'Winter Dawn' had the highest root dry weight. There

were no effects on total titratable acidity and soluble solids content among irrigation

programs. "Winter Dawn' had the highest total titratable acidity and the lowest soluble

solids content in most evaluations.

The results showed that reducing irrigation volumes from 5.4 L/m/day over a

period of 24 weeks to 1.8 L/m/day at a frequency of twice a day for the first eight weeks

and then 3.6 L/m/day at a frequency of twice a day for the remaining 16 weeks could

save an estimated of 11 million m3 of water per 24-week season for the Florida

strawberry industry as a whole. The suggested irrigation volumes and frequencies can

be used without causing plant stress, reducing yield and compromising postharvest

quality.









CHAPTER 1
INTRODUCTION

Florida is the second largest strawberry producing state in the U.S. (Tomlinson et

al., 2004). The planted strawberry area in Florida for 2008 was 3,359 ha, with a value of

production of $330 million (U.S.Department of Agriculture, 2010). Hillsborough County,

located in west central Florida, has the largest planted area in the state. In Florida

sandy soils, the amount of water that can be stored and available to the plants is limited.

Drip irrigation is the predominant irrigation system for strawberry production, but in order

to have the highest efficiency it requires proper design, installation and operation, which

includes knowing the water quality and the field's size, drainage characteristics, etc.

(Clark and Smajstrla, 1996). It also allows fertilizer application throughout the season

and reduces foliar diseases and weeds (by wetting only the soil in the beds and not in

the row middles) (Locascio, 2005). Precise, high-frequency, low-volume irrigation

reduces the potential for waterlogging and also helps to lower drainage requirements.

Irrigation scheduling consists of knowing when and how much water to apply in a

way that satisfies crop water needs with minimum leaching (Simonne and Hochmuth,

2006). Insufficient water application can result in crop stress and reduced yields. In

strawberries, Kruger et al. (1999) and Kirnak et al. (2003) have shown a positive

influence of proper irrigation on yield and fruit size and quality. Ostrowska and

Chelpiriski (2003) mentioned that insufficient water supply results in small, less aromatic

strawberry fruits and premature ripening. It was also found that there is a significant

effect of irrigation on strawberry flavor (Hoberg et al., 2002). Irrigation management has

been found to be directly linked not only to yield and economic value of vegetable crops,

but also to the long-term sustainability and environmental impact of vegetable









production (Simonne et al., 2005). In Florida, algal blooms have led to eutrophication,

degraded coastal water quality, and deterioration of coral reefs. Marine algal blooms are

caused by elevated nitrogen (N) and phosphorus (P) nutrient levels delivered to the

water bodies through leaching and run-off (Finkl and Charlier, 2003). According to

Smajstrla et al. (2002) other consequence of over-irrigation is the excessive waste of

water, fertilizers and energy (required for pumping from wells).

Modern agriculture has the challenge to produce increased quantities of fruits and

vegetables for a growing population, while dealing with ever higher production costs and

societal demands to minimize the negative environmental impact of production

practices. Under these circumstances, growing systems must be more efficient to be

competitive and sustainable. There is a wide range of irrigation practices used by

strawberry growers in Florida, in terms of irrigation volume and frequency of application.

Therefore, the objective of this study was to determine the influence of irrigation volume

and frequency on plant growth, fruit yield and postharvest quality. This information can

then be used to develop improved water use recommendations for production of

strawberry in west central Florida and other areas with soils and a climate similar to that

of west central Florida.

The null hypotheses of this research were:

a) Water volume and frequency of application have no effect on plant growth, yield,
and fruit quality.

b) The interaction between drip irrigation treatment and cultivar has no effect on
plant growth, yield, fruit quality or postharvest shelf life.









CHAPTER 2
LITERATURE REVIEW

Strawberry (Fragaria x ananassa) belongs to the Rosaceae Family. It resulted

from a natural hybrid between F. chiloensis, native to the west coast of North and South

America, and F. virginiana, native to the east coast of North America (Peres et al.,

2009). It is a widely-adapted crop grown in geographically diverse areas ranging from

low-latitude tropical and subtropical areas (e.g. Mexico, Colombia, Costa Rica, and

Florida) to high-latitude continental areas (e.g. Poland, Russia, Germany, Belgium, and

China) (Darnell et al., 2003). Strawberry is a herbaceous perennial plant with a central

stem or crown from which leaves, roots, stolons (runners), branch crowns and

inflorescences emerge (Hancock, 1999). Roots emerge from the base of crowns when

they come in contact with the soil. The roots begin branching at 2 to 5 cm and if

adequate water is available, they keep branching into a fibrous mass. There are 20 to

30 primary roots, hundreds of secondary, tertiary, and higher order roots (Hancock,

1999). According to Dana (1980) mentioned by Hancock (1999) there are up to 50 to

90% of the strawberry roots concentrated in the upper 10-15 cm of the soil.

Strawberry is a popular fruit with high visual appeal and desirable flavor but highly

perishable, being susceptible to mechanical injury, water loss, decay and physiological

deterioration (Shin et al., 2008). The principal strawberry currently grown in Florida is

'Strawberry Festival', a cultivar with firm fruit, a sturdy bush that does not yield large

quantities of fruit on any one date, and produces very few cull fruit. The external color of

fully mature fruit is deep red (Chandler et al., 2000).

'Winter Dawn' is a cultivar grown in Florida for its ability to produce high early

season yields. It is usually a relatively small plant with a shallow root system (Santos









and Chandler, 2009). The external color of fully mature fruit is mostly deep red and

glossy, although the color immediately surrounding the achenes is an orange red. Fruit

of 'Winter Dawn' are generally less firm than those of 'Strawberry Festival'. 'Florida

Radiance' is an offspring of 'Winter Dawn'. It tends to have a larger canopy than 'Winter

Dawn' and a more open plant habit than Festival. Its achenes are slightly sunken, giving

the fruit a smooth appearance. The external fruit color is a glossy bright to dark red

(Chandler et al., 2009).

Strawberry Postharvest Quality

Strawberries are one of the most perishable fruit crops. They have a high

metabolic rate and senesce in a relative short time, even without organisms causing

decay. Respiration rate of strawberries is high, ranging between 20 and 40 mg

C02/kg h at a temperature of 5C (Kader, 2002). Strawberries do not exhibit a

climacteric respiratory pattern, but their ripening is associated with biochemical changes

including increases in pectins, hemicelluloses and several enzymes associated with

anthocyanin and fatty acid biosynthesis (Hancock, 1999).

Fruit quality is a combination of appearance, including color and gloss, texture,

flavor, freshness, freedom of injury and decay and nutritional value (Mitchel et al.,

1996). Azodanlou et al. (2003) found that aroma and sweetness are two of the most

important quality attributes for strawberries consumers. Del Pozo-lnsfran et al. (2006)

described the flavor of fresh strawberries as highly dependent on both sweetness and

aroma-active compounds but that those sensory attributes can vary significantly from

harvest to harvest. Fruit ripeness, cultivar, irrigation, and fertilization are major factors

that affect taste quality of a product, in this case strawberries (Kafkas et al., 2007).

Jouquand et al. (2008) showed a high variation among strawberry genotypes grown in









Florida in terms of flavor, sweetness and tartness preferences and also that aroma

volatiles and sugar levels must be balanced to ensure a flavor appealing to consumers.

Soluble solids content of strawberry fruit is composed of sugars, acids, and other

substances dissolved in cell sap (Perkins-Veazie, 1995). Sugars are the main soluble

components in ripe strawberry fruit, with glucose, fructose, and sucrose accounting for

almost 99% of the total sugar content (Kafkas et al. 2007). According to Hancock (1999)

soluble solids and titratable acidity are dependent on strawberry cultivar and

environmental conditions. Kafkas et al. (2007) noted that the accumulation of organic

acids, ascorbic acid, and soluble sugars was strongly dependent on genotype. Del

Pozo-lnsfran et al. (2006) found significant differences in soluble solids and

phytochemical concentrations among strawberry genotypes grown in a winter hill

production system

Total titratable acidity is a measurement of the total acid concentration contained

within a food (Sadler and Murphy, 1998). In fruits, acids contribute to color stability, and

inhibit enzyme activity (Perkins-Veazie, 1995). The levels of organic acids present often

represent an important quality variable. In strawberry fruit the main acids are citric,

malic, succinic and quinic acids (Kays, 1997). Titratable acidity is generally expressed

as percent of citric acid, the predominant organic acid in strawberry. It ranges from

0.45% to 1.81%, depending on fruit maturity, cultivar, nutritional and environmental

impact (Perkins-Veazie, 1995). Titratable acidity gradually declines during ripening

(Hancock, 1999). In a study on strawberry fruit at six stages of maturity (white, pink, red

1/, red %, full red, and dark red) Menager et al. (2004) found that the levels of titratable

acidity were not different for the two first stages and then significantly decreased during









the latter stages of ripening. Chandler et al. (2003) suggested that to identify strawberry

genotypes that produce relatively high soluble solids in winter, fruit samples should be

collected and analyzed two or more times over the season. The fruit of some cultivars

tastes acidic because there are not enough sugars in the fruit to balance high acid

levels. Gunness et al. (2009) found that sweetness and sourness of strawberry rated

similarly for bulk puree and individual fruit samples.

Color can be defined as the interpretation by the brain of a light signal coming

from a sample. Color representation is a three-dimensional concept, various color

system have been suggested (Francis, 1998). In the CIE (International Commission on

Ilumination) L*, a* and b* (CIELAB) color space the lightness coefficient (L*) ranges

from black (0) to white (100). For any value of L*, the coordinate (a*, b*) locates the

color in a rectangular-coordinate grid perpendicular to the L* axis. Chroma (C*) is

calculated as (a*2 + b*2)2 and represents the hypotenuse of a right triangle created by

joining points (0, 0), (a*, b*), and (a*, 0). The hue angle (ho*) is defined as the angle

between the hypotenuse and 0 on the a* value (bluish-green/red-purple) axis

(McGuire, 1992). Shin et al. (2008) found that lightness, chroma and hue angle of

strawberry harvested at the white tip stage were greater during storage than of fruit

harvested red ripe, and also that the lower the temperature the higher the values of L*,

C* and ho of strawberry harvested with white tips.

Firmness of fruit relates to the storability and resistance to injury of products

during marketing (D0ving and Mage, 2002). Fruit firmness can be determined by

measuring penetration force using an Instron Universal Testing Machine (Instron

Corporation, Norwood, MA) (Kader, 2002). The handling and storage conditions to









which many products are exposed after harvest may also significantly alter their textural

properties. The loss of water due to improper control of relative humidity to which many

products are exposed after harvest can result in serious textural quality losses (Kays,

1997). Strawberries soften greatly between green and white ripening stages and

continue to soften as color development progresses (Perkins-Veazie, 1995). At harvest,

Shin et al. (2008) found that the firmness of white tip strawberries (74 N) was higher

than that of red ripe fruit (39 N). Manager et al. (2004) found that firmness decreased

from white to half red fruits and then appeared to remain constant level off. D0ving and

Mage (2002) found that firmness and soluble solids were mostly not significantly

correlated and that fruit firmness decreased with increased storage temperature.

Production System

The annual hill culture method for production, also known as plasticulture, is used

for strawberry production but also for other vegetables like tomato (Solanum

lycopersicum), bell pepper (Capsicum annuum), eggplant (Solanum melongena), and

watermelon (Citrullus lanatus); approximately 34,398 ha are planted with this production

system in Florida (U.S.Department of Agriculture, 2010). It is a management tool that

enables vegetable producers to obtain greater returns per unit by modifying the

microclimate around the crop (Lamont, 2005). Plasticulture includes soil fumigation, a

layer of polyethylene mulch over raised beds and drip irrigation. Lamont (1993) and

Simonne and Hochmuth (2010) mention some of the advantages of plasticuture: earlier

and higher overall yields, because the raised beds promote early season soil warming;

reduced evaporation since the soil is being covered; improved weed control; reduced

fertilizer leaching, as drip irrigation systems allow for better fertilizer management;

reduced soil compaction; elimination of root pruning; production of a cleaner product









since the product is not in contact with soil; reduced risk of flooding injury because

raised beds provide for better drainage; and finally, ability to double or triple crop. The

main disadvantages are the need for specialized equipment to make the raised beds

and lay the drip tape and plastic mulch; the cost of the plastic mulch and drip tape; and

the expense of removing and disposing of the plastic mulch and drip tape at the end of

the season.

Strawberries are picked with caps calyxess) attached. Fruit must be loosely held in

the hand without squeezing. Any squeezing of the fruit will cause bruising injury and

discoloration. Strawberries must be handled gently to ensure quality (Mitchell, 1996).

Mitcham and Mitchell (2002) mentioned that factors that can impact fruit quality, e.g.

preharvest disease control, field sanitation, harvest maturity fruit injuries at harvest and

packing, fruit disease and defects, exposure to light and heat, and rate of cooling. Kader

(2002) also mentions that appropriate temperature management, including rapid cooling

and maintenance of low pulp temperatures, is the most important factor to maximize

postharvest life (Kader, 2002). Nunes et al. (1995) found that when cooling of

strawberry fruit was delayed for 6 h at 30C, the berries were significantly softer, more

shriveled, had less attractive color, and the acidity, soluble solids content, sugar and

ascorbic acid levels were lower than in fruit that were quickly cooled.

Water Management

Florida has a humid subtropical climate and average annual rainfall for most of the

state is between 1270 and 1524 mm. However, the typically erratic distribution of rain

and Florida's predominantly sandy soils make frequent irrigation necessary in order to

avoid plant stress during drought conditions (Haman and Izuno, 2003). The aim of

irrigation management is to control plant water status for the purpose of maximizing









crop production while conserving water. Plant water status is determined by the

atmospheric and soil environment, and by water transport characteristics of the plant

(Hsiao, 1990). There is a difference between crop water requirements and irrigation or

production system water requirements. Crop water requirements refer to the water

needs for evapotranspiration (ET) and plant growth, and depend on crop development

and climatic factors. Irrigation requirements are determined by crop water requirements,

but also by the characteristics of the irrigation system, management practices and the

soil characteristics (Simonne and Dukes, 2009). In strawberry, more water is applied

than what plants actually use because losses due to leaching, evaporation, inefficient

application, and an inadequate ability to assess water requirements on a daily basis (El-

Farhan and Pritts, 1997).

Water transpired by plants and evaporation from the soil surface are generally

combined and defined as evapotranspiration (ET) which is the total water loss through

plants and soil surface (Kirda et al, 1999). Evaporation and transpiration occur

simultaneously and there is no easy way of distinguishing between the two processes.

Apart from water availability in the topsoil, evaporation from a cropped soil is mainly

determined by the fraction of solar radiation reaching the soil surface (Allen et al.,

1998). Transpiration increases during canopy development as a result of increasing

surface area. The enlarged canopy intercepts more radiation and therefore absorbs

more energy for transpiration (Hsiao, 1990). The rate of evaporation expresses the

amount of water lost from a cropped surface in units of water depth. While evaporation

is easily measured, transpiration is not. Values of ET for a crop are usually expressed

as the amount of water lost (inches, cm, mm) per unit of time (hour, day, week, month,









season, or year) (Whitty et al., 2002). In west central Florida, the historical Penman

reference method (ETo) ranges from 0 to 5.08 mm/day (0.08 to 0.20 inches/day)

(Simonne and Dukes, 2009). The weather variables affecting evapotranspiration are

radiation, air temperature, humidity, and wind speed.

In horticultural crops, changes in water status alter the general condition of the

product with economic losses being due to both decreased quality and product weight

(Kays, 1999). In zucchini, Bhella and Kwolek (1984) found that drip irrigation and plastic

mulch increased plant growth and yield, and reduced the number of days to bloom after

planting and the percentage of culls. In strawberries, Kruger et al. (1999) and Kirnak et

al. (2003) have shown a positive influence of proper irrigation on yield and fruit size and

quality in comparison to non-irrigated plants. Kirnak et al. (2001) also found that water

stress in strawberry plants reduced dry matter and chlorophyll content. In addition,

Kirschbaum et al. (2004) found that the greater yields for plants grown at field capacity

was a function of increased fruit number and weight, while the number of fruit per plant

was affected by the amount of water applied, rather than by irrigation frequency.

Ostrowska and Chelpiriski (2003) mentioned that water quantity affected yields, fruit

weight, and fruit ripening. Also, Hoberg et al. (2002) detected a significant effect of

irrigation on the flavor of strawberries.

Water deficit causes fruit yield reductions by decreasing flower number, fruit set,

numbers of fruit per plant, and fruit size. The effects on vegetative growth are more

pronounced than on yield (EI-Farhan and Pritts, 1997). Chandler and Ferree (1990)

evaluated the response of two strawberry cultivars to drought stress and found that it

reduced photosynthesis and transpiration, although the effect was more pronounced in









one cultivar than the other. Save et al. (1993) noted that strawberry plants can tolerate

drought by allowing the leaves to reach negative osmotic potentials, with accumulation

of solutes in less elastic tissues. This adaptation facilitates continued water uptake from

drying soil. Liu et al. (2007) evaluated the effects of partial root-zone drying, which

consisted in using irrigation to alternately wet and dry two spatially distinct parts of the

plant root system. They concluded that given the same amount of water, partial root-

zone drying had no advantage compared to deficit irrigation in maintaining plant water

status. Both treatments reduced yield. In addition to their direct effect on plant growth,

water deficits can affect crop management practices. For example the efficacy of many

herbicides and other pesticides depends on soil moisture; plants under drought stress

may not respond to foliar applied chemicals, or may be damaged by chemical burns.

Finally, nutrient utilization and fertilization practices are influenced by the moisture

status of the crop plants (Whitty et al., 2002).

Simonne et al. (2003) described irrigation scheduling as knowing when to start

irrigation and how much to apply, in a way that satisfies crop water needs, conserves

water, and does not leach mobile nutrients. Frequent, low-volume applications allow the

soil moisture content in the root zone to be maintained and are always better than

infrequent and long irrigation cycles (Haman and Smajstrla, 2005). According to Phene

and Beale (1976) daily low-rate application of nitrogen and potassium with a high-

frequency trickle irrigation system improved nutrient uptake efficiency and reduced

leaching loss of nutrients in humid regions. In cucumber, Ells et al. (1989) reported that

the best combination of high yield, high water use efficiency, and fewest number of

irrigation was obtained if cucumbers were irrigated when the scheduling program









determined that 40% of the available water was depleted, applying only 70% of the

water that the program indicated was required.

In strawberries, Dwyer et al. (1987) found that total production is increased by

irrigation applied at times of moderate water stress and that a few applications, applied

at the time required by the plants is as beneficial as numerous applications scheduled

routinely. Using tensiometers to schedule irrigation on strawberries, Serrano et al.

(1992) found that irrigation scheduling at -0.01 MPa was the most productive treatment.

Kirschbaum et al. (2004) suggested that the use of both hydrologic balance equation

and tensiometer would be adequate for planning irrigation schedules. According to their

results, the strawberries water requirement in the conditions of their study was around

800 mm/year and the fruit size was affected by water rates. Kruger et al. (1999) showed

that the irrigation of strawberries using the climatic water balance model could be a

decision-making tool because it is less labor intensive and time consuming than

tensiometer measurements. The soil was saturated each year to field capacity (100%

available water, AW) and then the soil moisture should range between 80% and 60%

AW for optimal plant growth. According to this model, irrigation should start when AW

falls below 60% in the layer between 0 and 20 cm below the surface by subtracting the

daily water balance (DW) from 100% AW on a daily basis. The daily water balance

DW=ET-P where ET is the evapotranspiration and P is rainfall measured in the field.

Hoppula and Salo (2007) suggested that tensiometers are a suitable tool for strawberry

irrigation scheduling because plants' water consumption varies considerably depending

on the growth stage, fruit load, and environmental factors. Finally, Gutal et al. (2005)

found that by applying water to the strawberry crop every other day with an amount









equal to 85% of the two-day pan evaporation gave the highest water use efficiency and

fruit yield.

The vegetable production in the west central Florida is primarily on flatwoods sites,

consisting of extremely flat Spodosols with the spodic horizon typically beginning at a

depth of 1 to 1.5 m (McNeal et al., 1995). Sandy soils consist mainly of large mineral

particles with very small percentages of clay, silt and organic matter and a significant

number of the pores in sandy soils are large enough to drain within the first 24 h due to

gravity and this portion of water is lost from the system before plants can use it (Haman

and Izuno, 2003). The available water for sand and fine sands is between a range of

33.3 to 83.33 mm/m (Haman and Izuno, 2003). Clark et al. (1993) noted that the sandy

soil (sandy, siliceous, hypothermic Alfic Haplaquod) evaluated in their study appeared to

have a practical horizontal wetting capillarityy) capacity of 125 to 200 mm (5 to 8 in) with

a drip irrigation rate of 1.5 to 1.9 L/h (0.4 to 0.5 gal/h). The soil can affect the quality of

the produce; for example sandy soils in windy locations can result in abrasions to the

surface of the product (Kays, 1999).

According to Simonne et al. (2003) an application uniformity of 85% to 95% is

expected from a new, well-designed drip irrigation system. Because trickle systems can

be operated frequently they are ideally suited to soils with a low water-holding capacity

(Clothier et al., 1985). Water moves across the soil surface away from the drip emitter

until the infiltration rate of the ponded area matches the emitter discharge rate; beyond

this, free-water moves into the soil by unsaturated flow (Clothier et al., 1985). A

maintenance plan will reduce the effects of the agents that reduce application

uniformity: small solids in suspension, organic matter, microorganisms, and chemical









residues (Simonne et al., 2003). Fertilizer application efficiencies increase when

fertilizer materials can be injected into the drip irrigation system (fertigation). Soluble

nutrients such as nitrogen and potassium are most often applied by drip irrigation by

injecting small amounts of nutrients through the season according to seasonal crop

nutrient requirements (Hochmuth, 2003).

Hardeman et al. (1999) found that for yield the trickle system was superior to

sprinkler for pepper and tomato and equivalent for snap bean; but fruit quality was

similar for both systems. In their experiment the trickle irrigation system applied 30%

less water than the sprinkler system. This would result in a significant cost savings if the

grower is paying for water. In strawberries, Rolbiecki et al. (2004) evaluated drip

irrigation and micro-sprinkler irrigation in a loose sandy soil; they found that drip

irrigation was superior in water use efficiency, but there were no differences among the

irrigation systems in terms of fruit size and number. Sprinkler irrigation is used to

establish bare root strawberry transplants and for freeze protection. For establishment,

plants are irrigated for approximately 8 h daily with overhead irrigation for 10 to 14 days.

Irrigation is provided to reduce the water stress caused by the damaged root system of

the transplant, the high surface temperature of the black mulch, the high ambient air

temperature, and dry weather condition at the time of transplanting (Golden et al.,

2003).

In terms of freeze protection, the irrigation water provides heat to the plant as the

temperature of the water drops to 0C and especially as it freezes. If the temperature of

the flowers or fruit stays above -1.1 C there will be no damage (Albregts and Howard,

1984). Because sandy soils have a low water holding capacity water moves rapidly









through these soils. Therefore there is a great potential for nitrate movement to

groundwater in these (Guimera et al., 1995). Simonne et al. (2006) described that using

drip tapes with a 20 to 30-cm emitter spacing and less than 900 L/100 m of irrigation

volume may reduce the risk of NO3 leaching on a sandy soil and provide optimum

irrigation management. According to Elrashidi et al. (2004) appropriate nutrient

management planning should be considered for cultivated fields to reduce nitrogen loss

from soils by leaching and scheduling irrigation according to depletion of available soil

water can help to reduce deep percolation (Guimera et al., 1995).

In Florida, marine algal blooms caused by elevated nitrogen and phosphorus

nutrient levels delivered to water bodies through leaching and run-off have resulted in

eutrophication, degraded coastal water quality, and deterioration of coral reefs (Finkl

and Charlier, 2003). One of the main sources of nitrates in groundwater is agricultural

fertilizers; reducing nutrient leaching through appropriate fertilization programs is a

desired practice for strawberry production and to support the current best management

practices in the state of Florida (Santos and Chandler, 2009). Guimera et al. (1995)

showed that a sustainable improvement of agricultural techniques can be achieved

while maintaining good standards for groundwater protection in strawberry crop

production.

Importance of the Study

The Southwest Florida Water Management District (2010) reported that public

water supply and agriculture represented 80% of the water use in the district. With a

growing population, water demand will increase every year. Contamination of ground

water resources has profound environmental implications that make necessary the

regulation and conservation of this resource. More efficient water use is one of the main









strategies for water conservation. With a planted area of 3,359 ha in 2008 (U.S.

Department of Agriculture, 2010), strawberry production has a high water requirement

for crop establishment, growth, and freeze protection. Strawberry growers in Florida use

a wide range of irrigation programs to grow the crop. Generating information for efficient

water use will help strawberry growers to maximize crop production and water savings.

For instance, if strawberry growers irrigate 1.5 h/day this represents a water volume of

5.4 L/m/day or 313,087 L/ha/week, which can be extrapolated to a total volume of 25.4

million m3 of water used by the west central Florida industry per year. However, if

strawberry growers irrigate only 1 h/day a volume of 3.6 L/m/day would be used, which

is equivalent to the average ETo for the strawberry season, and therefore an industry-

wide water savings of around 8.4 million m3 could be obtained.









CHAPTER 3
EFFECTS OF IRRIGATION VOLUMES AND FREQUENCIES ON THE GROWTH,
YIELD AND POSTHARVEST QUALITY OF 'STRAWBERRY FESTIVAL' GROWN ON
SANDY SOILS, 2008-09 SEASON

Materials and Methods

This study was conducted from October 2008 to March 2009 at the Gulf Coast

Research and Education Center of the University of Florida, Balm, Florida. The soil at

the experimental site is a sandy, siliceous, hyperthermic Oxyaquic Alorthod with 2.1%

organic matter and pH of 6.6. Planting beds were pre-formed with a standard bedder,

71 cm wide at the base, 61 cm wide on the top, and 25 cm high and spaced 120 cm

between centers. In early September 2008, the soil was fumigated with 350 kg/ha of

methyl bromide + chloropicrin (67/33, v/v). After fumigation a single-drip tape line (0.056

L/m/min, T-Tape Systems International, San Diego, CA) was buried 5 cm in all plots,

regardless of irrigation program, finally the beds were covered with black high-density

polyethylene mulch (0.04 mm-thick). No pre-plant fertilizer was used. The experimental

area was equipped with 15 L/min sprinklers for frost protection and crop establishment.

Plant nutrients were supplied to the crop through the drip lines three times per week

starting on December 8 with a hydraulic injector (Dosatron, Clearwater, FL) following

statewide recommendations (Peres et al., 2009), which represented approximately 10.8

L/m/week applied to all the experimental plots. Current IFAS recommendations for

insect and disease control were followed (Peres et al., 2009).

The treatments evaluated were combinations of three water volumes and two

irrigation frequencies. The water volumes were 1.8, 3.6 and 5.4 L/m/day, while the

irrigation frequencies were one and two cycles per day. The experimental design was a

randomized complete block design with four replications. On15 October 2008 bare-root









strawberry transplants from nurseries in Canada were transplanted in double rows 38

cm apart, 20 plants per 7.6 m plot with a 1.5 m long non-treated buffer zone at the end

of each plot. The cultivar evaluated was 'Strawberry Festival'. After transplanting,

overhead irrigation was used for 8 hours for the first 10 days to ensure plant

establishment (the amount of water used was approximately 480,000 L/ha/day). The

irrigation volumes were transformed into irrigation times and controlled with electronic

timers (Nelson SoloRain, Walla Walla, WA). Treatments receiving a single irrigation per

day were watered between 8 and 9 am each morning, whereas plots receiving two

cycles per day were watered between 12 pm and 1 pm in addition to the morning

irrigation.

Strawberry plant diameter and chlorophyll content readings were taken at 6, 12,

and 18 weeks after transplanting (WAT). Plant diameter was determined using five

plants per plot randomly selected and measuring the widest part of the plant. Ten

recently mature leaves per plot were randomly selected to measure the chlorophyll (Chl)

content with a SPAD-502 (Minolta, Ramsey, NJ), an instrument developed to measure

the chlorophyll content of leaves as an indirect estimate of the nitrogen status of plants

(Martinez and Guiamet, 2004). A numerical SPAD (Soil Plant Analysis Development)

unit, ranging from 0 to 80 is calculated by the chlorophyll meter and used to estimate

the Chl content. Foliar nutrient concentrations were determined at 6, 12 and 24 WAT. A

sample of ten recently matured leaves was randomly collected from each experimental

plot. Samples were dried at 700C in a forced-air dryer for 48 h. Once dried, leaf samples

were ground using a tissue mill (Thomas Scientific Wiley mill, Swedesboro, NJ) and

they were sent for analysis to a commercial lab. Root and shoot dry weight (DW) was









determined at the end of the season. Five plants of each experimental plot were

removed from the field and dried at 700C in a forced-air dryer for one week. The dry

tissue was weighed in a precision balance (Ohaus Adventurer, Ohaus Corporation, Pine

Brook, NJ).

Marketable fruit with the attached calyx was harvested twice a week and the

weight was recorded for 24 harvests during the season starting on December 17, 2008.

Marketable strawberry fruit was defined as fruit over 10 g in weight and physiologically

mature with more than 80% of red skin, free of mechanical defects and insect or

disease injury. Early yield was considered as the fruit weight recorded from the first 10

harvests. Initial fruit quality (pre-storage) was evaluated at harvest dates of January 19

(14 WAT), February 16 (18 WAT), February 27 (19 WAT), and March 16 (22 WAT)

2008. Between four and ten fruit from each plot were placed in two 473 mL clamshells

(Highland Corporation, Inc., Mulberry, FL) and transported to the Postharvest

Horticulture Laboratory, Horticultural Sciences Department in Gainesville, Florida. One

clamshell per plot was stored overnight in a cooler at 1 oC to be evaluated the next day.

The fruit stored at 1 C were allowed to warm to room temperature (approximately 220C)

the next day. At that time three fruit per treatment were used to measure external color

at equator on opposite sides of the fruit with a Minolta CR-400 chroma meter (Minolta,

Ramsey, NJ). Color was expressed as lightness (L*), hue angle (ho*) and chroma (C*)

value. The calyxes were removed and a transverse section of 10 mm of the fruit was

cut to measure the internal firmness (3 mm deformation) on opposite sides of the

transverse section with an Instron 4411 (Instron Corporation, Norwood, MA), equipped

with a 3-mm diameter tip and a 5-kg load cell with a crosshead speed of 0.83 mm/s.









This test measured individual internal fruit firmness based in the resistance of the tissue

to deformation by the probe.

Six fruit per treatment were frozen to be processed for later evaluations. Frozen

samples were later thawed at room temperature, blended in a Hamilton Beach Model

908 blender (Proctor-Silex, Inc, Washington, NC), and centrifuged at 15,000 rpm for 20

min on a Beckman Model J2-21 centrifuge (Beckman Coulter, Inc., Fullerton, CA). The

juice obtained was filtered and then frozen in 20 mL plastic vials for later evaluations.

Frozen juice vials were thawed at room temperature (approximately 22C). Five drops

of the filtered supernatant were used for the measurements of soluble solids content

(Brix) using a digital refractometer (Reichert AR 200, Depew, NY). Total titratable

acidity (TA) was measured diluting 6 mL of sample in 50 mL of distilled water. It was

stirred (Metrohm 728 stirrer, Metrohm USA, Inc, Westbury, NY) and titrated (Titrino 719

S, Metrohm USA Inc, Westbury, NY). Total titratable acidity was calculated with the

miliequivalent factor for citric acid (0.064 g per mEq), the major organic acid in

strawberries.

One clamshell of fruit per plot harvested 19 and 22 WAT was stored in a cooler at

5C for eight days. This temperature is notably higher than the recommendation of 0C,

but was selected to represent typical commercial handling conditions and with the

purpose to accelerate postharvest decay and determine shelf life. These fruit were

evaluated after eight days at 5C for postharvest quality (post-storage), and warmed to

room temperature (approximately 22C).The variables evaluated were external color

(L*, C* and ho*), firmness, soluble solids content (oBrix) and total titratable acidity

following the same procedures described above for initial quality evaluations.









Collected parametric data were analyzed using Statistix 9 software (Analytical

Software, Tallahassee, FL). Main effects were examined for significance (P<0.05) with a

regression analysis to determine linear effects within each irrigation frequency. Irrigation

volumes were separated using standard errors of the treatment means.

Results and Discussion

2008-09 Strawberry Season Environmental Conditions

The average environmental conditions from October 2008 to March 2009 from the

Florida Automated Weather Network (2010) are shown in Table 3-1. The average of

rain per month was 31.4 mm and three freeze events occurred on January 21 to 23,

February 5 to 6 and February 21, 2008, with minimum temperatures of -3.3C, -4.70C, -

2.1 C, -2.7C, -1.4C and -0.2C, respectively (daily averages in Appendix A).

Plant Diameter and Chlorophyll Content

There were no significant differences in plant diameter between any of the

irrigation volumes 6 WAT, ranging from 23.5 to 27 cm for one cycle/day and from 22.6

to 25.1 cm for two cycles, and 12 WAT, where the range was between 34.9 and 36.8

cm for one cycle/day and between 35.3 and 36.7 cm for two cycles/day., and there were

no significant differences for the irrigation volumes using the frequency of one cycle per

day at 18 WAT, ranging from 36.9 to 37.5 cm (Table 3-2). There were significant

differences among 1.8, 3.6 and 5.4 L/m/day applied in two cycles per day at 18 WAT

(Figure 3-1), plant diameter ranged from 35.9 to 39.4 cm increasing as the irrigation

volume increased. Plant diameter of plots irrigated with 1.8, 3.6 and 5.4 L/m/day in one

cycle/day ranged between 23.7 and 27 cm at 6 WAT, between 34.9 and 36.8 cm at 12

WAT and between 36.9 and 37.5 cm at 18 WAT. Plant diameter of plots irrigated with

1.8, 3.6 and 5.4 L/m/day applied in two cycles/day ranged between 22.6 and 25.1 cm









and between 35.3 and 36.7 cm at 6 and 12 WAT, respectively. There was no significant

effect of the irrigation programs on chlorophyll content at 6, 12, and 18 WAT (Table 3-

2). For 'Strawberry Festival', the Chl content of the irrigation programs of 1.8, 3.6 and

5.4 L/m/day applied one cycle /day ranged between 37.4 and 40.3 SPAD value at 6

WAT, between 42.9 and 44.3 SPAD value at 12 WAT and 44.7 and 45.9 SPAD value at

18 WAT. While applying 1.8, 3.6 and 5.4 L/m/day in two cycles per day the Chl content

at 6 WAT ranged between 37.6 and 39.3 SPAD value, at 12 WAT between 43.5 and

44.1 SPAD value and at 18 WAT between 45.1 and 47.3 SPAD value.

Root and Shoot Dry Weight

There were no significant differences among the irrigation programs for root dry

weight, ranging from 3.46 to 5.5 grams (Table 3-3); however, there were for shoot dry

weight. Shoot dry weight of plants irrigated in one cycle/day decreased for 1.8 to 3.6

L/m/day but increased with 5.4 L/m/day, ranging from 33.36 to 41.27 g (Figure 3-1).

Whereas shoot DW of plants irrigated in two cycles per day increased as the irrigation

volume increased, ranging between 22.82 and 29.30 g.

Foliar Nutrient Concentration

Six weeks after transplant, there were significant differences among the irrigation

programs on nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), iron (Fe),

boron (B), manganese (Mn), and zinc (Zn) but not for potassium (K), sulfur (S) and

copper (Cu) (Table 3-4). All the nutrients were in the adequate range according to Peres

et al. (2009). The N foliar content of the irrigated plots in two cycles per day ranged

between 3.30% and 3.18%, decreasing as the irrigation volume increased (Figure 3-2).

While the P content increased with the increase in irrigation volume when the plots were

irrigated in one cycle/day, ranging from 0.27% to 0.36%, it decreased in the plots









irrigated in two cycles/day ranging between 0.42% and 0.32% (Figure 3-2). Ca, Mg, B,

and Fe content for the plots irrigated in one cycle/day was higher when the irrigation

volume was 1.8 L/m/day and decreased with volumes of 3.6 and 5.4 L/m/day ranging

between 1.33% and 0.59%, 0.66% and 0.38%, 40.15 and 30.01 mg/L, 66.25 and 56.92

mg/L respectively (Figures 3-3 and 3-4) but it was the opposite for the content of Zn in

plots irrigated in one cycle per day, it ranged from 25.11 to 34.63 mg/L (Figure 3-5).

Figure 3-5 also shows that the Mn content decreased for 3.6 and 5.4 L/m/day when they

were applied in one cycle/day, ranging from 47.20 to 36.97 mg/L, but there was an

increased when the irrigation volumes applied in two cycles per day increased, ranging

from 36.94 to 42.68 mg/L.

Twelve weeks after transplant there were significant differences among the

irrigation programs on B, Zn, and Mn foliar content, but not on N, K, Ca, Mg, S, Fe, Cu,

and B (Table 3-5). All the nutrients were in the adequate range according to Peres et al.

(2009). B foliar content decreased when the plots were irrigated with high volumes in

both frequencies, ranging between 51.72 and 37.19 mg/L in one cycle/day and 51.91 to

33.91 mg/L in two cycles per day (Figure 3-6). When the irrigation volume was applied

in two cycles per day the Zn and Mn foliar content diminished when the irrigation

volume increased, ranging from 37.45 to 27.10 mg/L and from 55.33 to 35.57 mg/L,

respectively (Figures 3-6 and 3-7).

At the end of the season (24 WAT), there were significant differences among the

irrigation programs for P, Ca, Cu, and B; but there were not for N, K, Mg, S, Zn, Mn, and

Fe (Table 3-6). All the nutrients were in the adequate range according to Peres et al.

(2009). The P content increased when the plots were irrigated with the higher irrigation









volumes (Figure 3-8) for both irrigation frequencies (one and two cycles/day) ranging

from 0.26% to 0.30% and from 0.24% to 0.29% for one and two cycles/day respectively.

The foliar content of Ca and Cu of the plots irrigated in two cycles/day was lower for 1.8

L/m/day than for 3.6 and 5.4 L/m/day (Figures 3-8 and 3-9) ranging between 1.52% and

1.68% (Ca) and between 8.75 and 10.75 mg/L (Cu) and finally the B content of the plots

irrigated in one cycle per day decreased as the irrigation volume increased, ranging

from 107.75 to 59.50 mg/L (Figure 3-9).

Pre-storage Strawberry Fruit Quality

There were no significant effects of the irrigation programs on the fruit quality

parameters total titratable acidity (TA), soluble solids content, and on external color (C*,

h* and L*) (Table 3-7) at the initial (pre-storage) evaluation 14 WAT. There was a

significant effect of the irrigation programs on fruit firmness when the plots were

irrigated in one cycle/day (Figure 3-10) but not for the plots irrigated in two cycles per

day. The strawberry firmness increased as the irrigation volume increased for the plots

irrigated in one cycle/day, ranging from 0.60 to 0.78 N. TA, soluble solids content,

external color (L*, C* and ho*), and firmness had no significant differences among the

irrigation programs (Table 3-8) at the pre-storage evaluation 18 WAT. There were not

significant differences among the irrigation programs on TA, soluble solids content, C*,

ho*, and firmness (Table 3-9); but there was on L* for the frequency of two cycles per

day at the pre-storage evaluation 19 WAT; fruit from the plots irrigated with 1.8, 3.6 and

5.4 L/m/day had L* values that ranged between 31.44 and 32.96, being 5.4 L/m/day the

one with the highest L* value (Figure 3-11). At the pre-storage evaluation 22 WAT, for

soluble solids content, C*, ho*, and firmness there were no significant differences

among the irrigation programs (Table 3-10), but there were for TA and L* for the









irrigation frequency of one cycle per day. Both TA and L* (Figure 3-12) of the fruit from

plots irrigated in one cycle/day had the highest value for 1.8 L/m/day and diminished

with higher volumes. TA ranged from 0.66% to 0.83% and L* ranged from 30.74to

32.03.

Post-storage Strawberry Fruit Quality

At the post-storage evaluation 19 WAT there were significant differences on TA

from harvested fruit from plots irrigated in one cycle/day and on L* of fruit from plots

irrigated in two cycles/day. For soluble solids content, C*, ho*, firmness, TA (two

cycles/day) and L* (one cycle/day), however, there were no significant differences

(Table 3-11). After storage, TA of fruit from plots irrigated with 1.8 L/m/day in one

cycle/day was higher than the values from plots irrigated with 3.6 and 5.4 L/m/day,

where the TA was almost equal, it ranged from 0.76% to 0.84%, while L* (two

cycles/day) was lower on fruit from irrigated plants with 1.8 L/m/day and increased with

higher volumes ranging from 32.16 to 34.8 (Figure 3-13). At the post-storage evaluation

22 WAT, fruit harvested at the end of the strawberry season had significant differences

in firmness and C* when the irrigation volume was applied in two cycles/day. There

were not significant differences on TA, soluble solids content, L*, ho*, C* and firmness

for the frequency of one cycle/day (Table 3-12). Fruit firmness after one week of storage

of plots irrigated in two cycles/day was higher when the volume was 1.8 L/m/day and

lower for volumes of 3.6 and 5.4L/m/day, ranging from 33.36 to 41.27 g and the

opposite was for C*, where the lowest volume had the lowest C* and it increased as the

volume increased, ranging from 31.78 to 33.62 (Figure 3-14).









Early and Total Yields

Early yields were not influenced by any of the irrigation programs. For 'Strawberry

Festival', irrigation programs did not affect early yields, which ranged between 7.8 and

9.0 t/ha. There was not a significant effect on total yields when irrigation volumes were

applied once per day, with an average of 27.3 t/ha. However, when the irrigation

volumes were applied twice per day, there was a significant effect on total yields. The

lowest total yield was found in plots irrigated twice per day with 1.8 L/m/day, whereas

the highest fruit yields were obtained in plots irrigated with 3.6 or 5.4 L/m/day, ranging

between 29.6 and 30.0 t/ha (Figure 3-15).

The results indicate that at the beginning of the season, when plants do not have a

large root system and the evapotranspiration rate was lower, nutrient absorption was

different depending on the irrigation program applied. Irrigation frequency had a strong

effect on of macro and micro nutrients absorption. In the case of B, Ca, Mg, Mn, and Fe

applying 1.8 L/m/day in one cycle per day made the strawberry plants absorb a higher

content of those nutrients; but a lower foliar content of Zn and P. Applying the irrigation

programs in two cycles per day only had effect on the absorption of N, P and Mn.

However, differences in foliar nutrient concentration at the beginning of the season did

not mean higher plant diameter and higher early yields. The plant tissue analysis

showed that the nutrients were in adequate range, even for the lowest volume (1.8

L/m/day). This volume could be used by growers in both frequencies at the beginning of

the season without affecting plant growth. In the middle of the season (12 WAT) the

irrigation programs only had an effect on Mn, Zn and B for the frequency of two cycles

per day, plants from plots irrigated with the lowest volume had the highest content of

those nutrients and the same happened for B content of plants irrigated in one









cycle/day. Differences on some foliar nutrients did not mean bigger plants because

there was no effect on plant diameter and chlorophyll content. At the end of the season,

with a volume of 1.8 L/m/day applied in two cycles per day, Cu, P and Ca content was

low, while for the irrigation frequency of one cycle per day, B content was higher with

1.8 L/m/day than with 3.6 and 5.4L/m/day. This result is similar to what Kirnak et al.

(2003) found with a reduced irrigation volume at the end of the strawberry season, P

and Ca foliar concentration in mature leaves was low and that might have affected the

total yields of the plants irrigated with the lowest volume, particularly with the frequency

of two cycles per day.

Plant growth was influenced at 18 WAT, plants from plots irrigated in two cycles

per day had higher plant diameter with the highest water volume. Shoot dry weight at

the end of the season had a similar pattern when the highest volume resulted in the

highest shoot dry weight for both irrigation frequencies and particularly when the water

volume was applied in one cycle per day. Both plant diameter and shoot dry weight had

the lowest values when 1.8 L/m/day was applied in two cycles per day. Such response

was most likely because of the high evapotraspiration, air and soil temperature in west

central Florida at the end of the strawberry season. The effect of irrigation on shoot dry

weight of strawberry plants was also found by Kirnak et al. (2003) with higher shoot dry

weight in plants irrigated with the highest volume. Strawberries could be irrigated with

1.8 L/m/day during the first 8 WAT without significantly reducing early yields. Irrigation

should occur only once per day when lower water volumes are utilized. In contrast, total

yields were influenced by irrigation programs. Total yield increased in plots irrigated with

3.6 and 5.4 L/m/day per season applied in two cycles; but increasing irrigation volumes









to 5.4 L/m/day did not increase strawberry yields even though the plant diameter and

shoot dry weight of the plants irrigated with 5.4 L/m/day the highest at the end of the

season. These results appear similar to those reported by Dwyer et al. (1987), Kirnak et

al. (2003), and Blatt (1984) who found an effect of irrigation scheduling on strawberry

yield. The lowest total yield was obtained in plots irrigated with 1.8 L/m/day in two cycles

per day and this can be related with the low plant diameter and low shoot DW obtained

from the same irrigation volume. As mentioned by Simonne and Duke (2009) the crop

water requirements includes the water needs for evapotranspiration and plant growth. It

is possible that the lowest water volume only covered the evapotranspiration needs but

not the plant growth which directly affects the plant yield, in addition with the water

wasted because the efficiency of the drip irrigation is around 85% to 95%. According to

Simonne et al. (2006) frequent and short irrigations may waste water and reduced

irrigation uniformity due to a large proportion of the irrigation cycle used for system

charge and flush. Serrano et al. (1992) also found yield reductions associated with the

reduction on total assimilation rate because the assimilatory surface area decreased in

plants irrigated at low soil water potentials.

In terms of postharvest quality, water volume influenced fruit firmness at 14 WAT,

fruit harvested from plots irrigated with 1.8 L/m/day in one cycle/day were softer than

fruit from plots irrigated with higher water volumes. According to Morris and Sistrunk

(1991) mentioned by Prange and DeEII (1997) strawberry fruit is softest after rain. It

only rained the harvesting day at 14 WAT and the effect was stronger on fruit from plots

irrigated with 1.8 L/m/day. There was an effect of water volume applied in one cycle/day

on TA, the percentage of TA on strawberry fruit harvested at 19 WAT was high when









1.8 L/m/day was applied. The same response was obtained in the pre-storage

evaluation at 22 WAT for the same irrigation volume and frequency; meaning that

reducing the irrigation volume at the end of the season might increase the TA. This

irrigation program had also the highest L* among the treatments. Irrigating with two

cycles per day had an effect on fruit firmness after storage. It was higher in fruit from

plots irrigated with 1.8 L/m/day. Chroma had a smaller value for 1.8 L/m/day in two

cycles per day than for the other two irrigation volumes, which means that the intensity

of color of the strawberry fruit was high when the water was applied in two cycles per

day.

In general, for strawberry grown in sandy soils, increasing the water volume to

more than 3.6 L/m/day (average evapotranspiration of the strawberry season) did not

increase 'Strawberry Festival' early and total yields, but it might increase leaching and

waste of water and fertilizers. On the other hand, irrigating with a volume of 1.8 L/m/day,

and most likely lower volumes through the season, would result in reduction in plant

growth and yield. Further research should show if the same effects on yields are found

to confirm these results. Scheduling strawberry irrigation based on weather conditions

to satisfy the strawberry water needs can be less labor intensive and time consuming as

mentioned by Kruger et al. (1999). A strawberry grower could irrigate with a water

volume of 3.6 L/m/day in one or two cycles per day, although the frequency of two

cycles per day can result in higher yields. The irrigation volume of 1.8 L/m/day in one or

two cycles per day could be used at the beginning of the season when plant size is still

small. Then the volume could be increased to 3.6 L/m/day when the size of the plants









gets bigger and the water needs increase to satisfy crop water requirements and at the

same time using the resources efficiently.









Table 3-1. Average environmental conditions from October 2008 to March 2009 from
FAWN0 weather report for Balm, Florida.
Air Temperature (C) Soil Temperature (C) n Relative Solar
Month humidity irradiation
Avg Min Max Avg Min Max (mm) (%) (w/m2)

October 22.3 1.6 33.1 24.6 19.5 26.8 35.6 73.0 185.2

November 16.6 0.6 31.9 20.1 16.6 23.1 37.8 71.0 154.0

December 17.3 1.2 29.1 18.2 15.6 20.3 34.5 75.0 136.6

January 14.5 -4.6 29.0 16.7 12.0 19.8 37.1 71.0 148.8

February 15.1 -2.6 29.5 16.6 12.0 19.5 12.7 66.0 186.6

March 19.0 1.0 31.4 19.3 14.9 21.8 30.5 69.0 215.4

"Florida Automated Weather Network


Table 3-2. Effects of irrigation volumes and frequencies on 'Strawberry Festival'
plantdiameter and leaf chlorophyll content at 6, 12, and 18 weeks after
transplant(WAT). 2008-09 Season.
Chlorophyll content
Volume Frequency Plant diameter (cm) Chl content
(SPAD value)
6 12 18 6 12 18
(L/m/day) (cycles/day) 6 1 1 6 1 1
(L/m/day) (cycles/day) WAT WAT WAT WAT WAT WAT
1.8 24.0 36.1 37.5 40.3 44.3 44.8

3.6 1 23.5 34.9 36.9 37.4 44.1 44.7

5.4 27.0 36.8 37.3 38.7 42.9 45.9

Significance (P<0.05) NS NS NS NS NS NS

1.8 22.8 35.3 35.9 39.3 43.5 45.1

3.6 2 22.6 36.2 36.4 37.6 44.1 46.9

5.4 25.1 36.7 39.4 39.0 43.5 47.3

Significance (P<0.05) NS NS NS NS NS

NS,* Not significant and significant at P<0.05, respectively.









Table 3-3. Effects of irrigation volumes and frequencies on 'Strawberry Festival' root
and shoot dry weight at 25 weeks after transplant. 2008-09 Season.

Volume Frequency Root dry weight Shoot dry weight

(L/m/day) (cycles/day) (g) (g)

1.8 5.42 33.36

3.6 1 4.05 29.02

5.4 5.24 41.27

Significance (P<0.05) NS

1.8 3.46 22.82

3.6 2 5.50 28.57

5.4 4.74 29.30

Significance (P

NS,* Not significant and significant at P<0.05, respectively.









Table 3-4. Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar nutrient concentration at 6 weeks
after transplant. 2008-09 Season.
Volume Frequency N P K Ca Mg S Fe Cu B Zn Mn

(L/m/day) (cycles/day) (%) (mg/L)

1.8 3.14 0.27 1.98 1.33 0.66 0.19 66.25 6.37 40.15 25.11 47.20

3.6 1 3.11 0.36 2.04 0.68 0.41 0.18 56.69 6.42 31.46 28.94 35.53

5.4 3.00 0.36 2.09 0.59 0.38 0.18 56.92 6.44 30.01 34.63 36.97

Significance (P
1.8 3.30 0.42 2.11 0.66 0.42 0.19 58.97 6.60 32.97 34.20 36.99

3.6 2 3.21 0.31 1.88 1.15 0.62 0.18 62.50 5.80 37.68 27.26 38.87

5.4 3.18 0.32 2.05 1.08 0.56 0.18 63.10 6.43 36.64 27.64 42.68

Significance (P

NS,* Not significant and significant at P<0.05, respectively.









Table 3-5. Effects of irrigation volumes and
after transplant. 2008-09 Season.


frequencies on 'Strawberry Festival' foliar nutrient concentration at 12 weeks


Volume Frequency N P K Mg Ca S Fe Cu Zn Mn B

(L/m/day) (cycles/day) (%) (mg/L)

1.8 3.17 0.36 2.45 0.40 0.87 0.21 145.65 12.73 34.53 64.69 51.72

3.6 1 3.10 0.41 2.52 0.42 0.87 0.22 160.64 13.79 35.94 54.88 41.20

5.4 3.25 0.39 2.38 0.41 0.88 0.21 144.79 12.09 32.66 48.89 37.19

Significance (P
1.8 3.24 0.40 2.42 0.42 0.90 0.22 155.12 14.31 37.45 55.33 51.91

3.6 2 3.27 0.41 2.56 0.44 0.95 0.22 161.21 13.75 33.85 44.28 42.95

5.4 3.09 0.35 2.13 0.39 0.80 0.19 126.48 11.10 27.10 35.57 33.91

Significance (P

NS,* Not significant and significant at P<0.05, respectively.









Table 3-6. Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar nutrient concentration at 24 weeks
after transplant. 2008-09 Season.
Volume Frequency N P K Mg Ca S Zn Mn Fe Cu B

(L/m/day) (cycles/day) (%) (mg/L)

1.8 2.74 0.26 2.00 0.45 1.67 0.19 34.00 97.33 107.25 10.25 107.75

3.6 1 2.75 0.29 2.17 0.47 1.61 0.19 30.00 54.50 100.75 10.00 61.50

5.4 2.56 0.30 2.06 0.50 1.68 0.19 28.50 68.00 106.00 10.00 59.50

Significance (P
1.8 2.75 0.24 1.86 0.48 1.52 0.19 25.75 67.25 97.25 8.75 77.00

3.6 2 2.65 0.29 2.37 0.44 1.60 0.19 29.75 67.00 96.75 9.50 85.00

5.4 2.62 0.29 1.97 0.50 1.68 0.19 27.00 54.50 106.25 10.75 61.25

Significance (P

NS,* Not significant and significant at P<0.05, respectively.









Table 3-7. Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit quality; pre-storage (8 days at 5C)
evaluation at14 weeks after transplant. 2008-09 Season.
Soluble
Total titratable
Volume Frequency acidity solids External fruit color Firmness
content
(L/m/day) (cycles/day) (%) (oBrix) Lightness Chroma hue angle (N)

1.8 0.90 7.98 33.12 32.62 29.52 0.60

3.6 1 0.90 8.23 32.77 34.08 29.20 0.70

5.4 0.90 7.95 32.68 33.57 29.74 0.78

Significance (P
1.8 0.91 8.43 32.78 33.74 29.78 0.68
3.6 2 0.85 7.75 32.89 32.80 29.67 0.70

5.4 0.82 7.40 32.13 33.34 27.80 0.70

Significance (P

NS,* Not significant and significant at P<0.05, respectively.









Table 3-8. Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit quality; pre-storage (8 days at 5C)
evaluation at 18 weeks after transplant. 2008-09 Season.
Soluble
Total titratable
Volume Frequency acidity solids External fruit color Firmness
content
(L/m/day) (cycles/day) (%) (oBrix) Lightness Chroma hue angle (N)

1.8 0.67 8.13 33.62 32.96 29.37 0.60

3.6 1 0.73 8.88 32.87 32.41 25.02 0.54

5.4 0.71 7.70 33.22 32.90 28.05 0.54

Significance (P
1.8 0.73 8.63 32.80 33.27 27.58 0.55
3.6 2 0.71 8.48 33.38 33.11 29.44 0.53

5.4 0.76 8.50 33.57 32.32 28.87 0.58

Significance (P

NS,* Not significant and significant at P<0.05, respectively.









Table 3-9. Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit quality; pre-storage (8 days at 5C)
evaluation at 19 weeks after transplant. 2008-09 Season.
Soluble
Total titratable
Volume Frequency acidity solids External fruit color Firmness
content
(L/m/day) (cycles/day) (%) (oBrix) Lightness Chroma hue angle (N)

1.8 0.82 8.53 32.70 32.52 28.60 0.75

3.6 1 0.78 7.48 32.48 32.34 27.91 0.80

5.4 0.73 7.95 31.75 32.76 28.49 0.85

Significance (P
1.8 0.77 8.80 31.44 32.26 27.85 0.90
3.6 2 0.78 8.13 31.48 31.94 28.90 0.87

5.4 0.81 8.03 32.88 32.96 28.26 0.95

Significance (P

NS,* Not significant and significant at P<0.05, respectively.









Table 3-10. Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit quality pre-storage (8
evaluation at 22 weeks after transplant. 2008-09 Season.


days at 5C)


Soluble
Total titratable
Volume Frequency acidity solids External color Firmness
content
(L/m/day) (cycles/day) (%) (oBrix) Lightness Chroma hue angle (N)

1.8 0.83 8.88 32.03 27.26 28.89 0.75

3.6 1 0.60 7.50 29.99 23.11 23.29 0.73

5.4 0.66 7.80 30.74 26.04 27.24 0.57

Significance (P
1.8 0.70 9.55 32.24 27.67 29.14 0.64

3.6 2 0.67 7.38 31.42 27.24 24.92 0.73

5.4 0.74 7.55 32.25 28.30 27.25 0.64

Significance (P

NS,* Not significant and significant at P<0.05, respectively.









Table 3-11. Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit quality post-storage (8 days at 5C)
of fruit harvested at 19 weeks after transplant. 2008-09 Season.

Volume Frequency Total titratable acidity Soluble solids content External color Firmness

(L/m/day) (cycles/day) (%) (oBrix) Lightness Chroma hue angle (N)

1.8 0.84 8.53 34.11 34.76 26.83 0.76

3.6 1 0.76 7.48 34.42 36.41 29.51 0.96

5.4 0.76 7.95 33.12 33.55 27.98 0.85

Significance (P<0.05) *NS NS NS NS NS

1.8 0.85 8.80 32.16 31.79 26.08 0.96

3.6 2 0.83 8.13 34.80 36.18 27.21 0.83

5.4 0.79 8.03 33.55 33.62 27.08 0.60

Significance (P<0.05) NS NS NS NS NS


NS,* Not significant and significant at P<0.05, respectively.









Table 3-12. Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit quality post-storage (8 days at 5C)
evaluation of fruit harvested at 22 weeks after transplant. 2008-09 Season.
Soluble
Total titratable
Volume Frequency acidity solids External color Firmness
content
(L/m/day) (cycles/day) (%) (oBrix) Lightness Chroma hue angle (N)

1.8 0.69 8.95 30.54 29.78 32.81 0.70

3.6 1 0.65 9.10 30.70 30.18 28.96 0.65

5.4 0.72 8.65 31.25 31.50 31.18 0.76

Significance (P<0.05) NS NS NS NS NS NS

1.8 0.72 9.20 30.10 31.78 31.13 0.77

3.6 2 0.72 9.28 31.27 36.18 29.44 0.60

5.4 0.72 8.93 31.33 33.62 29.89 0.63

Significance (P

NS,* Not significant and significant at P<0.05, respectively.














39


E
o 38


E 37
E
0 36
a,.

35


34
1.8 3.6 5.4
A


46
44
42
40
S38
36
34
-o 32
30
o 30
28
26
24
22
20
18
1.8 3.6 5.4
Irrigation volume (L/m/day)
B


-o 1 cycleiday --2 cycles/day


Figure 3-1. Effects of irrigation volumes and frequencies on 'Strawberry Festival' A)
plant diameter (cm) at 18 weeks after transplant, B) shoot dry weight 25
weeks after transplant. 2008-09 Season.












3.4

3.3

3.2

3.1

z
2.9

2.8

2.7

2.6

2.5
1.8 3.6 5.4
A



0.5


0.5


0.4


S0.4


0.3


0.3


0.2
1.8 3.6 5.4
Irrigation volume (Limiday) B


1 cycle/day --2 cycles/day


Figure 3-2. Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
nutrient content at 6 weeks after transplant. A) nitrogen (N), B) phosphorus
(P). 2008-09 Season.












1.5
1.4
1.3
1.2
1.1
1.0
0.9
7 0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
1.8 3.6 5.4

A



0.8


0.7


0.6


0.5


0.4


0.3


0.2
1.8 3.6 5.4
Irrigation volume (L/m/day)
B


-- 1 cycle/day --2 cycles/day

Figure 3-3. Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 6 weeks after transplant. A) calcium (Ca), B) magnesium (Mg).
2008-09 Season.











50
48
46
44
42
40
38
2J 36
E 34
m 32
30
28
26
24
22
20
1.8 3.6 5.4

A


75



70



65


E
a) 60
L.


55



50
1.8 3.6 5.4
Irrigation volume (L/m/day) B

1 cycle/day -E-2 cycles/day

Figure 3-4. Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 6 weeks after transplant. A) boron (B), B) iron (Fe). 2008-09
Season.











40
38
36
34
32
30
2 28
E 26
N 24
22
20
18
16
14
1.8 3.6 5.4

A


54
52
50
48
46
44
42
E
40
38
36
34
32
30
1.8 3.6 5.4
Irrigation volume (L/m/day) B



o 1 cycle/day --2 cycles/day



Figure 3-5. Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 6 weeks after transplant. A) zinc (Zn), B) manganese (Mn). 2008-
09 Season.











60
58
56
54
52
50
48
46
J 44
E 42
m 40
38
36
34
32
30
28
26
1.8 3.6 5.4

A


42

40

38

36

34

S32
E
S30

28

26

24

22
1.8 3.6 5.4
Irrigation volume (L/m/day) B


-o- 1 cycleiday --2 cycles/day

Figure 3-6. Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 12 weeks after transplant. A) boron (B), B) zinc (Zn). 2008-09
Season.






60














75


65


b 55
E

45 -


35


25
1.8 3.6 5.4
Irrigation volume (L/m/day)

-o 1 cycle/day -M-2 cycles/day



Figure 3-7. Effects of irrigation volumes and frequencies on 'Strawberry Festival'
manganese (Mn) foliar content at 12 weeks after transplant. Season 2008-09.

































61











0.35


0.30





0.25





0.20
1.8 3.6 5.4
A



1.9


1.8


1.7


1.6
U

1.5


1.4


1.3
1.8 3.6 5.4
Irrigation volume (L/m/day) B



-o 1 cycle/day --2 cycles/day



Figure 3-8. Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 24 weeks after transplant. A) phosphorus (P), B) calcium (Ca).
2008-09 Season.















11



10


E
S9
U


8



7
1.8 3.6 5.4

A


130

120

110

100

90

2 80
E 70

60

50

40

30

20
1.8 3.6 5.4
Irrigation volume (L/m/day) B


o 1 cycle/day -M-2 cycles/day


Figure 3-9. Effects of irrigation volumes and frequencies on 'Strawberry Festival' foliar
content at 24 weeks after transplant. A) copper (Cu), B) boron (B). 2008-09
Season.













0.9


0.8 -


0.7


0.6 -


0.5


0.4
1.8 3.6 5.4
Irrigation volume (L/m/day)

1 cycle/day --2 cycles/day


Figure 3-10. Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
firmness (N) pre-storage (8 days at 5C) at 14 weeks after transplant. 2008-
09 Season.














34


33


32


31


30
1.8 3.6 5.4
Irrigation volume (L/m/day)


-o 1 cycleday --2 cycles/day


Figure 3-11. Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
lightness (L*) pre-storage (8 days at 5C) at 19 weeks after transplant. 2008-
09 Season.











1.0


0.9


o' 0.8



CO
0.7


0.6
1-

0.5


0.4
1.8 3.6 5.4

A


34


33


32

L*
31


30


29


28
1.8 3.6 5.4
Irrigation volume (Llmlday) B


o 1 cycle/day --2 cycles/day


Figure 3-12. Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
pre-storage (8 days at 5C) analysis at 22 weeks after transplant. A) total
tritatable acidity (% citric acid), B) lightness (L*). 2008-09 Season.











1.00


0.95

0.90

0.85

0.80

o 0.75 -

S0.70
1-
0.65

0.60
1.8 3.6 5.4
A


36

35

34

33
L*
32

31

30

29

28
1.8 3.6 5.4
Irrigation volume (L/m/day) B


-- 1 cycle/day --2 cycles/day


Figure 3-13. Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
post-storage (8 days at 5C) analysis of fruit harvested at 19 weeks after
transplant. A) total titratable acidity (% citric acid), B) lightness (L*). 2008-09
Season.
























































Irrigation volume (L/miday)


-> 1 cycle/day -M-2 cycles/day


Figure 3-14. Effects of irrigation volumes and frequencies on 'Strawberry Festival' fruit
post- storage (8 days at 5C) analysis of fruit harvested at 22 weeks after
transplant. A) firmness (N), B) chroma (C*). 2008-09 Season.


I


i
















































3.6
Irrigation volume (L/m/day)


-- 1 cycle/day -4-2 cycles/day

Figure 3.15. Effects of irrigation volumes and frequencies on 'Strawberry Festival' early
yield (A) and total yield (B). 2008-2009 Season.





69









CHAPTER 4
EFFECTS OF IRRIGATION VOLUMES AND FREQUENCIES ON THE GROWTH,
YIELD AND POSTHARVEST QUALITY OF 'STRAWBERRY FESTIVAL', 'FLORIDA
RADIANCE' AND 'WINTER DAWN' ON SANDY SOILS, 2009-10 SEASON

Materials and Methods

This study was conducted from October 2009 to March 2010 at the Gulf Coast

Research and Education Center of the University of Florida, Balm, Florida. The soil at

the experimental site is a sandy, siliceous, hyperthermic Oxyaquic Alorthod with <1.5%

organic matter and pH of 6.6. Planting beds were pre-formed with a standard bedder,

71 cm wide at the base, 61 cm wide on the top, and 25 cm high and spaced 120 cm

between centers. In August 2009, the soil was fumigated with 350 kg/ha of methyl

bromide + chloropicrin (50/50, v/v). After the fumigant injection a single-drip tape line

(0.056 L/m/min, T-Tape Systems International, San Diego, CA) was buried 5 cm in all

plots, regardless of irrigation program, finally the beds were covered with black high-

density polyethylene mulch. No pre-plant fertilizer was used. The experimental area was

equipped with 15 L/min sprinklers for frost protection and crop establishment. Plant

nutrients were supplied to the crop through the drip lines three times per week starting

on December 07 with a hydraulic injector (Dosatron, Clearwater, FL) following statewide

recommendations (Peres et al., 2006), which represented approximately 10.8 L/m/week

applied to all the experimental plots. Current recommendations for insect and disease

control were followed (Peres et al., 2009).

Eighteen treatments were tested resulting from combining six irrigation programs

and three strawberry cultivars ('Strawberry Festival', 'Florida Radiance' and 'Winter

Dawn'). The irrigation programs were combinations of three water volumes and two

irrigation frequencies. The water volumes were 1.8, 3.6 and 5.4 L/m/day, while the









irrigation frequencies were one and two cycles per day. The experimental design was a

split-plot design with four replications with the irrigation programs in the main plots and

the cultivar in the subplots. Bare-root 'Winter Dawn' and 'Florida Radiance' strawberry

transplants from nurseries in Canada were planted on 13 and 14 October 2009,

respectively, while the 'Strawberry Festival' transplants were transplanted on 27

October 2009. All the cultivars were transplanted in double rows 38 cm apart, 20 plants

per 7.6 m plot with a 1.5 m non-treated buffer zone at the end of each plot. After

transplanting, overhead irrigation was used for 8 hours for the first 10 days to ensure

plant establishment (the amount of water used was approximately 480,000 L/ha/day).

The irrigation volumes were transformed into irrigation times and controlled with

electronic timers (Nelson SoloRain, Walla Walla, WA). Treatments receiving a single

irrigation per day were watered between 9 and 11 am each morning, whereas plots

receiving two cycles per day were watered between 3 pm and 4 pm in addition to the

morning irrigation.

Daily soil water content was determined at 12.7 cm (5 in) with a Soil Scout TDR

200 Probe (Spectrum Technologies, Plainfield, III.), every other week at 8 am during the

strawberry season. Strawberry plant diameter and chlorophyll content readings were

taken at 6, 14, and 17 weeks after transplanting (WAT). Plant diameter was determined

using five plants per plot randomly selected and measuring the widest part of the plant.

Ten recently mature leaves per plot were randomly selected to measure the chlorophyll

content (Chl) with a Chlorophyll meter SPAD-502 (Minolta, Ramsey, NJ), an instrument

developed to measure the chlorophyll content of leaves as an indirect estimate of the

nitrogen status of plants (Martinez and Guiamet, 2004). A numerical SPAD (Soil Plant









Analysis Development) unit, ranging from 0 to 80 is calculated by the chlorophyll meter

and used to estimate the Chl content. Foliar nutrient concentrations were determined at

6, 14 and 17 weeks after transplant. A sample of ten recently matured leaves was

randomly collected from each experimental plot. Samples were dried at 700C in a

forced-air dryer for 48 h. Once dried, leaf samples were ground using a tissue mill

(Thomas Scientific Wiley mill, Swedesboro, NJ) and sent for analysis to a commercial

lab. Root and shoot dry weight (DW) was determined at the end of the season. Five

plants of each experimental plot were removed from the field and dried at 700C in a

forced-air dryer for one week. The dry tissue was weighted individually in a precision

balance (Mettler Toledo PG2002-S, Mettler Toledo, Columbus, OH).

Marketable strawberry fruit with the attached calyx were harvested twice a week

and the weight was recorded for 24 harvests during the season starting on December

07, 2009. Marketable strawberry fruit were defined as fruit over 10 g in weight and

physiologically mature with more than 80% of red skin, free of mechanical defects,

insect or disease injury. Early yield was considered as the yield from the first 10

harvests. Postharvest fruit quality (pre-storage) was evaluated at harvest dates of

January 28 (14 WAT), February 18 (17 WAT), and March 11 (20 WAT) 2010.

Fruit from each plot was used for the measurement of external fruit color. It was

measured at equator on opposite sides of the fruit with a Minolta CR-400 chroma meter

(Minolta, Ramsey, New Jersey). Color was expressed as lightness (L*), hue angle (ho*)

and chroma (C*) value. Strawberries from each plot were squeezed and the juice was

used to measure soluble solids content (oBrix) using a digital refractometer (Atago,

Itabashi-ku, Tokyo). Fruit from each plot were frozen to be processed the next day to









determine total titratable acidity (TA). Frozen samples were later thawed at room

temperature (approximately 220C), then blended in a blender (Waring Commercial

blender, Model 7011, Waring Products Inc, Torrington, CT), and centrifuged at 8490

rpm for 20 min (Sorvall Legend RT and a Sorvall Biofuge stratus, Kendro Laboratory

Products Inc., Newtown, CT). The obtained juice was filtered and frozen in 20 mL

plastic vials for later evaluation. Frozen juice vials were allowed to thaw at room

temperature (approximately 220C). Total titratable acidity was measured diluting 6 mL of

sample on 50 mL of distilled water, then it was stirred (Metrohm 802 stirrer, Metrohm

USA Inc, Westbury, NY) and titrated (848 Titrino Plus, Metrohm USA Inc, Westbury,

NY). TA was calculated with the miliequivalent factor for citric acid (0.064 g per mEq),

the major organic acid in strawberries.

Between four and ten fruit from each plot were placed in 473 mL clamshells

(Highland Corporation, Inc., Mulberry, FL) and storage in a cold room at 70C for 8 days.

This temperature is notably higher than the recommendation of 0C, but was selected to

represent typical handling conditions and with the purpose to accelerate postharvest

decay and determine shelflife. Post-storage evaluations included visual quality of the

fruit inside the clamshell, for this variable a descriptive test was used to obtain a normal

distribution of the data points (Heintz and Kader, 1983). External color (L*, C* and ho*),

soluble solids content (oBrix) and total titratable acidity were also determined using the

same procedures described above for initial quality evaluations (pre-storage).

Collected parametric data were analyzed using Statistix 9 software (Analytical

Software, Tallahassee, FL) .General linear model procedure (ANOVA split-plot analysis)

was used to determine the significance (P<0.05) of the individual factors (Irrigation









programs and cultivars), and their interactions. Irrigation programs were separated

using standard errors of the treatment means.

Results and Discussion

2009-10 Strawberry Season Environmental Conditions

The average environmental conditions from October 2009 to March 2010 from the

Florida Automated Weather Network (2010) are shown in Table 4-1. The total amount of

rain was 488 mm during the season (50% in March, 2010). There were four freezing

events, on December 29, from January 04 till January 13, 2009, February 14, 15 and

26, 2010, (daily averages on Appendix A).Water content of the soil used at the

experimental site was between 10% and 14% during the strawberry season (Figure 4-

1), that range can be considered as field capacity in sandy soils. Soil water content

higher than 10% means that there was enough water to satisfy the plant water needs.

Plant Diameter and Chlorophyll Content

There were no significant differences in plant diameter among the irrigation

programs and cultivars at 6 WAT, ranging from 22.4 to 24.3 cm. At 14 and 17 WAT,

there was a significant difference among cultivars, ranging between 28.4 and 33.8 cm at

14 WAT and between 25.7 and 31.0 cm at 17 WAT, but not among irrigation programs

at 14 and 17 WAT (Table 4-2). 'Strawberry Festival' had the highest plant diameter 14

WAT, 33.8 cm, followed by 'Winter Dawn', 31.8 cm while 'Florida Radiance had the

smallest diameter 14 and 17 WAT, 28.4 and 25.7 cm respectively. Plant diameter

among irrigation programs ranged from 22.4 and 24.3 cm 6 WAT, from 30.6 and 31.8

cm 14 WAT and from 28.3 to 29.7 cm 17 WAT. There was no interaction irrigation

program x cultivar, significant differences were found in Chl content among strawberry

cultivars at 6, 14 and 17 WAT (Table 4-3). The first evaluation at 6 WAT showed that









'Winter Dawn' had the highest SPAD value of 46.6, followed by 'Florida Radiance' and

'Strawberry Festival' with values of 45.3 and 41.0. The second and third evaluation

showed the same pattern obtained in the first evaluation, the range of the second

evaluation was between 46.2 and 48.9 and for the third evaluation was between 43.7

and 48.7. There were no significant differences among irrigation programs; Chl content

ranged between 43.9 and 44.9 at 6 WAT, between 46.9 and 48.2 at 14 WAT and

between 45.4 and 46.4 at 17 WAT. There was no effect of irrigation program x cultivar.

Root and Shoot Dry Weight

There were no significant differences among the irrigation programs for root dry

weight; the range was between 5.08 and 5.7 grams (Table 4-4). There were significant

differences among the strawberry cultivars. 'Winter Dawn' had the highest root dry

weight with a value of 6.33 g, followed by 'Strawberry Festival' with a value of 5.55 g,

the lowest value (4.88 g) was for 'Florida Radiance'. There were effects of the irrigation

program x cultivar for shoot dry weight (Table 4-5). The highest value of shoot dry

weight was for 'Strawberry Festival' from plots irrigated with 1.8 L/m/day in two cycles

per day, while the lowest values were for 'Florida Radiance' irrigated with the six

programs.

Foliar Nutrient Concentrations

Foliar analysis at 6, 14 and 17 WAT showed that all nutrients were in adequate

range based on the values described by Peres et al. (2009). There were no effects of

irrigation program x cultivar. There were no significant differences among irrigation

programs for nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), iron (Fe),

boron (B), manganese (Mn), zinc (Zn), potassium (K), sulfur (S) and copper (Cu) but

there were among cultivars for N, K, Ca, Mg, S, Zn and Mn (Table 4-6). For N and Mg









'Strawberry Festival' had the lowest values and 'Winter Dawn' the highest, ranging

between 3.14% and 3.43% for N and 0.43% and 0.49% for Magnesium. 'Florida

Radiance' had the highest percentage of K and Ca, and for S and Zn the order from

lowest to highest was 'Winter Dawn'<'Florida Radiance' <'Strawberry Festival' with

values ranging from 0.20% to 0.21% for S and from 34.71 to 42.00 mg/L for Zn. Mn

content was higher for 'Winter Dawn', followed by 'Strawberry Festival' and 'Florida

Radiance' with values ranging from 69.83 to 48.08 mg/L.

In the following foliar analysis made at 14 WAT (Table 4-7), there were significant

differences among irrigation programs for P, K, S, B and Mn; and there were significant

differences between cultivars for all the nutrients evaluated. The values of P ranged

between 0.40% and 0.44%, being the strawberries from the plots irrigated with 1.8

L/m/day applied in one cycle the ones with the lowest % of P. K content ranged from

2.14% to 2.42%, the lowest value was for the program of 5.4 L/m/day applied in one

cycle/day and the highest 1.8 L/m/day applied in one cycle/day. S and B content in the

strawberry leaves ranged from 0.21% to 0.22% and from 40.00 to 45.92 mg/L,

respectively, in both cases 5.4 L/m/day applied in both frequencies had the lowest

values and 1.8 L/m/day had the highest values. Mn concentration ranged from 68.58 to

89.08 mg/L, this nutrient was obtained in a lower concentration in the strawberries plots

irrigated with 3.6 L/m/day in one and two cycles/day, and the highest value was

obtained from plants irrigated with 1.8 L/m/day. In terms of cultivars, 'Strawberry

Festival' had the lowest percentages of N, K, Ca, Mg, with values of 3.18%, 2.27%,

0.90% and 0.43%, respectively; intermediate values of S, Fe, Cu, and Mn, with values

of 0.22% 67.33 8.46 and 83.96 mg/L, respectively, while the highest values were for









P (0.44%) and B (47.46 mg/L). 'Florida Radiance' had the lowest values for P, B, and

Mn, the values were 0.40%, 39.58 and 60.63 mg/L, respectively; intermediate values for

Ca (1.01%), Mg (0.45%), and Zn (28.38 mg/L), and it had the highest values for N

(3.61%), K(2.43%), S (0.23%), Fe (71.42 mg/L) and Cu (8.67 mg/L). Finally, 'Winter

Dawn' had the lowest values for S (0.21%), Fe (64.21 mg/L), Cu (8.00 mg/L), and Zn

(25.92 mg/L), intermediate values for N (3.33%), K (2.30%), P (0.43%), and B (40.17

mg/L) and the highest values for Ca, Mg and Mn with values of 1.02%, 0.47% and 91.63

mg/L, respectively.

In the foliar analysis at17 WAT (Table 4-8) there were significant differences

among the irrigation programs for N, P, K, S, B, Zn and Mn. For N 3.6 L/m/day in one

cycle/day had the highest content, 3.41%, while the lowest value was for 5.4 L/m/day in

one cycle per day with a value of 3.19%. The volumes of 1.8 and 3.6 L/m/day in one

and two cycles/day had the highest % of P with values ranging from 0.44% to 0.45%.

The highest K content was in leaves from plots irrigated with 5.4 L/m/day in two cycles

per day (2.41%) while the lowest was for plants irrigated with the same volume but in

one cycle/day (2.17%). The irrigation volume of 5.4 L/m/day applied in one and two

cycles/day had the lowest values for S (0.20% and 0.20%) and B (39.69 and 39.85

mg/L). The highest Zn concentration was obtained in plants irrigated with 3.6 L/m/day in

one cycle per day with a value of 27.21 mg/L, while the lowest was for the irrigation

program of 5.4 L/m/day in two cycles per day with a value of 23.65 mg/L. For Mn, the

program of 3.6 L/m/day in two cycles per day with a value of 78.06 mg/L was the lowest;

the highest value was 112.17 mg/L for the program on 1.8 L/m/day applied in one cycle

per day. There were significant differences between cultivars for all the nutrients









analyzed. For N and K, 'Florida Radiance' had the highest values, 3.49% (N) and 2.42%

(K), followed by 'Winter Dawn' with values of 3.33% (N) and 2.31% (K) and the lowest

values were for 'Strawberry Festival', 3.14% (N) and 0.86% (K). The P concentration for

'Winter Dawn' was 0.48%, while for the other two cultivars was 0.40%. 'Florida

Radiance' had the highest % of Ca, 1.08%, followed by 'Winter Dawn', 0.97%, and

'Strawberry Festival' 0.86%. For Mg, the order from highest to lowest was 'Winter

Dawn'> "Florida Radiance'> 'Strawberry Festival' with values of 0.44%, 0.41% and

0.37% respectively. 'Florida Radiance' had the highest values for S, Fe and Cu content

with values of 0.22 %, 74.67 and 9.88 mg/L, 'Winter Dawn' had values of 0.20% (S),

64.74 mg/L (Fe) and 8.22 (Cu), and 'Strawberry Festival' had values of 0.20% (S),

63.56 mg/L (Fe) and 8.46 mg/L (Cu). 'Strawberry Festival' had the highest value for B

(51.38 mg/L), followed by 'Florida Radiance' and 'Winter Dawn' with values of 42.22 and

40.97 mg/L, respectively. The highest values for Zn were 'Florida Radiance' (27.06

mg/L) and 'Strawberry Festival' (25.58 mg/L), 'Winter Dawn' was the lowest with a value

of 23.64 mg/L. Finally, for Mn 'Winter Dawn' and 'Strawberry Festival' had the highest

values of 111.98 and 101.12 mg/L, respectively; while 'Florida Radiance' had the lowest

value of 70.56 mg/L. There was no effect of program x cultivar.

Pre-storage Strawberry Fruit Quality

There were no significant differences in total titratable acidity, soluble solids

content, and external color expressed as L*, C* and ho* among the irrigation programs

in the pre-storage evaluation at14 WAT (Table 4-9). TA ranged between 1.30% and

1.33%, for soluble solids content it ranged from 7.65 to 8.44oBrix, for L* it ranged

between 35.02 and 36.07, C* ranged between 39.73 and 40.97 and ho* ranged from

27.51 to 29.47. However, there were significant differences among the strawberry









cultivars. For TA, 'Strawberry Festival' had the lowest value (1.30%) while 'Florida

Radiance' had a value of 1.38% and 'Winter Dawn' a value of 1.52%. The soluble solids

content was higher for 'Strawberry Festival' (9.16oBrix) followed by 'Florida Radiance'

(7.89oBrix) and 'Winter Dawn' (6.53Brix). For external color, L* was higher for

'Strawberry Festival' with a value of 36.82, followed by 'Winter Dawn' with a value of

35.52 and 'Florida Radiance' with a value of 34.69; C* values were 39.13, 40.36 and

40.49 for 'Strawberry Festival', Florida Radiance' and Winter Dawn', respectively. Hue

angle was higher for 'Strawberry Festival' with a value of 31.66, followed by 'Winter

Dawn' with a value of 28.09 and 'Florida Radiance' with a value of 26.41.

For TA, soluble solids content, L*, and ho* there were no significant differences

among the treatments in the pre-storage evaluation at 17 WAT (Table 4-10). The range

for TA was between 1.06% and 1.13%, for soluble solids content between 6.71 Brix and

7.13oBrix, and for external color between 34.96 and 35.57 for L*, between 41.19 and

41.67 for C*and from 27.99 to 29.45 for ho*. There were significant differences among

strawberry cultivars. 'Strawberry Festival' and 'Florida Radiance' had values of TA of

1.18% and 0.93% while 'Winter Dawn' had the highest value, 1.20%. The soluble solids

contents were 6.42oBrix and 6.79oBrix for 'Florida Radiance' and 'Winter Dawn' and

7.64oBrix for 'Strawberry Festival'. Values of L* were 33.78, 35.22 and 37.29 for 'Florida

Radiance', 'Strawberry Festival' and 'Winter Dawn', respectively. 'Strawberry Festival'

and 'Florida Radiance' had C* values of 39.49 and 39.87, while 'Winter Dawn' had a

value of 45.01. Hue angle was low for 'Florida Radiance' (27.45) and it was higher for

'Winter Dawn' and 'Strawberry Festival' with values of 29.15 and 30.25, respectively,









meaning that 'Florida Radiance' had a more red color than the other two cultivars. There

were no effects of irrigation programs x cultivar.

There were no significant differences among the irrigation programs for total

titratable acidity, soluble solids content, L*, C*, and ho* at 20 WAT (Table 4-11). TA

ranged from 0.99% to 1.05% and the soluble solids content from 7.59oBrix to 8.22oBrix.

It ranged between 33.02 and 33.99 for L*, between 37.58 and 38.90 for C* and from

24.55 to 26.70 for ho*. There were significant differences among cultivars. 'Strawberry

Festival' and 'Winter Dawn' had values of TA of 1.07% and 1.08%, while 'Florida

Radiance' had a value of 0.92%. 'Strawberry Festival' had the highest value of soluble

solids content (9.03oBrix) whereas 'Florida Radiance' and 'Winter Dawn' had values of

7.52oBrix and 6.99oBrix. For external color variables 'Strawberry Festival' and 'Winter

Dawn' had higher values of L*, 34.27 and 34.19, than the 'Florida Radiance' value of

32.75. 'Winter Dawn had a value of 40.11, the highest for C*, followed by 'Florida

Radiance' with a value of 38.83 and 'Strawberry Festival' with a value of 36.56. For ho*,

the highest value was for 'Strawberry Festival' (27.47) followed by 'Winter Dawn' (25.82)

and 'Florida Radiance' (23.77). There were no effects of irrigation program x cultivar.

Post-storage Strawberry Fruit Quality

Post-storage analysis included TA, soluble solids content (oBrix), external color

(L*, C*and ho*) and visual quality at 14 WAT (Table 4-12). There were no significant

differences among irrigation programs for any of the variables evaluated. The range for

TA was between 1.26% and 1.33%, for soluble solids content between 6.73oBrix and

7.12oBrix. L* of fruit ranged from 32.93 to 34.02, C* ranged between 39.66 and 40.98

and ho* had values that ranged from 27.11 to 29.65. Visual quality of the fruit had values

between 6.18 and 6.96. There were significant differences between the strawberry









cultivars in all variables evaluated except for visual quality, which ranged from 6.50 to

6.83. 'Florida Radiance' had the lowest value of acidity (1.04%) followed by 'Strawberry

Festival' with a value of 1.37% and the cultivar with the highest value of acidity was

'Winter Dawn' (1.50%). For soluble solids content, 'Strawberry Festival' had the highest

value, 7.95oBrix, followed by 'Florida Radiance' and 'Winter Dawn' with values of

6.44oBrix and 6.32oBrix. External color of 'Strawberry Festival' had a L* value of 34.32,

followed by 'Winter Dawn' with a value of 33.13 and 'Florida Radiance' with a value of

32.91. C* had values of 41.31, 41.25 for 'Winter Dawn' and 'Florida Radiance',

respectively, and 'Strawberry Festival' had a value of 38.31. Hue angle was higher for

'Strawberry Festival' (29.98), followed by 'Winter Dawn' with a value of 28.37 and a

value of 26.64 for 'Florida Radiance'. There were no effects of irrigation program x

cultivar.

At 17 WAT there were significant differences among irrigation programs for L* and

h* but not for TA, soluble solids content and visual quality (Table 4-13). For L*,

irrigation programs of 1.8 and 5.4 L/m/day in two cycles/day had the lowest values,

32.90 and 32.83 respectively and the highest value was for the irrigation program of 3.6

L/m/day in two cycles/day with a L* value of 34.03. Programs of 1.8, 3.6 and 5.4

L/m/day in one cycle/day had values of 33.73, 33.10 and 33.64, respectively. Hue angle

was higher for the program of 3.6 L/m/day in two cycles/day (26.87), followed by 5.4,

1.8 and 3.6 L/m/day in one cycle/day with values of 26.66, 26.01 and 25.72,

respectively. The lowest values were 25.35 and 25.28 for the programs of 5.4 and 1.8

L/m/day in two cycles per day. TA ranged from 1.11% to 1.19%, the soluble solids

content had values within a range of 8.29oBrix and 8.53oBrix, the range of the visual









quality values was between 5.84 and 6.56. There were significant differences among

cultivars for TA, soluble solids content, L*, ho* and visual quality. For TA, 'Winter Dawn'

and 'Strawberry Festival' had values of 1.23% and 1.19% and the lowest value was for

'Florida Radiance' with a 1.03% value. Soluble solids content were higher for

'Strawberry Festival' (9.32oBrix), followed by 'Florida Radiance' and 'Winter Dawn' with

values of 7.98oBrix and 8.07oBrix, respectively. The value of L* was higher for 'Winter

Dawn' (34.80), followed by 'Strawberry Festival' (33.69) and 'Florida Radiance' with a

value of 31.63. Hue angle was higher for 'Strawberry Festival' (28.29) followed by

'Winter Dawn' (25.59) and 'Florida Radiance' (24.07). Visual quality of 'Strawberry

Festival' (6.74) and 'Florida Radiance' (6.46) were higher than 'Winter Dawn' (5.22).

There was an effect of irrigation program x cultivar for C* (Table 4-14) but not for the

rest of the variables analyzed. The higher values of C* were for the cultivar 'Winter

Dawn' irrigated with 1.8, 3.6 and 5.4 L/m/day in one cycle/day with values of 43.06,

41.02, and 41.73, respectively and 3.6 and 5.4 L/m/day in two cycle/day with values of

42.72 and 41.25. The lowest values were for 'Strawberry Festival' for 1.8 L/m/day in one

cycle/day and 3.6 L/m/day in two cycles/day with values of 36.75 and 36.53 and 'Florida

Radiance' with values of 36.1 and 35.86 for the programs of 1.8 and 3.6 L/m/day in one

cycle per day.

There were significant differences for the irrigation programs for visual quality but

not for TA, soluble solids, L*, C* and ho* at 20 WAT (Table 4-15). TA ranged between

0.97% and 1.03%, for soluble solids content the values had a range from 8.00oBrix to

8.50%, L* ranged between 31.37 and 33.08, C* ranged from 37.89 to 39.45 and ho* had

a range from 23.95 to 26.41. Visual quality was higher for 1.8 L/m/day in one cycle/day









while the lowest was for the program of 3.6 L/m/day in two cycles per day. There were

significant differences among cultivars for the variables evaluated but not for visual

quality, which had a range from 6.92 to 7.02. 'Strawberry Festival' had the highest TA

with a value of 1.05%, followed by 'Winter Dawn' with a value of 1.08% and 'Florida

Radiance' had the lowest value of 0.89%. 'Strawberry Festival' had also the highest

value of soluble solids content (9.24oBrix) while 'Florida Radiance' and 'Winter Dawn'

had values of 7.88oBrix and 7.61 Brix. For external color, 'Strawberry Festival' and

'Winter Dawn' had the highest values of L*, 32.87 and 32.48, respectively, followed by

'Florida Radiance' with a value of 31.07. C* value for 'Winter Dawn' was the highest

(40.14) and 'Strawberry Festival' and 'Florida Radiance' had values of 37.62 and 38.50.

'Strawberry Festival' had the highest ho with a value of 27.72, followed by 'Winter Dawn'

(25.60) and 'Florida Radiance' with a value of 22.97. There were no effects of irrigation

program x cultivar.

Early and Total Yield

For early and total yield there were no significant differences among the irrigation

programs (Table 4-16). For early yields the range was between 2.31 and 2.52 t/ha while

the total yields ranged from 10.30 to 11.30 t/ha. There were significant differences

among the cultivars for both early and total yield. The highest early yield was obtained

by 'Florida Radiance', followed by 'Strawberry Festival' with a value of 2.26 t/ha and

'Winter Dawn' with an early yield of 2.14 t/ha. Although 'Winter Dawn' had the lowest

early yield, it had the highest total yield for the season 2009-10, with a value of 13.40

t/ha. 'Strawberry Festival' had a total yield of 10.13 t/ha and 'Florida Radiance' had the

lowest total yield, 8.73 t/ha.









The 2009-10 strawberry season for was colder than the 2008-09 strawberry

season in west central Florida. According to Florida Automatic Weather Network (2010),

between December 2009 and January 2010there were 14 days of temperatures below

0C. The sprinklers are usually turned on when the temperatures reach 2C, which

meant approximately 24 days under freeze protection, where the strawberry plants were

covered with a layer of ice. Some consequences of this weather conditions were

thousands of gallons of water spent in freeze protection, crop losses and inability to

harvest. A published critical temperature for strawberry injury in bloom and small fruit is

-2o C (Michigan State University Extension, 2004), temperature reached 7 times in a

time frame of 10 days. The results of the present research might have been affected by

these freeze events; the air and soil temperatures were lower than the first season and

the large amount of days under freeze protection might have slowed the strawberry

plants metabolism. Durner and Poling (1987) described that cluster production on

'Earliglow' was enhanced with 50 hours of chilling (4.40C) but with 150 hours at the

same temperature it was delayed by 3 weeks. It was found that cooler day/night

temperatures (18/12C) shifted biomass from leaves to roots but it also was a good

temperature for fruit growth (Wang and Camp, 2000). Soil temperature can affect the

growth of the roots, initiation of branching, orientation and direction of growth but

genotypic differences between cultivars can also be found (Kaspar and Bland, 1992).

The results of the present research showed that irrigation programs did not influence

the root weight but there were differences among the cultivars, 'Winter Dawn' had in the

order of 33% more dry root weight than 'Florida Radiance', it also had more chlorophyll

content through the season, which meant a good nitrogen status.









Even though the plant tissue analysis showed that the strawberry plant nutrient

content of all the irrigation programs and cultivars were between normal ranges, 'Winter

Dawn' had the highest total yield and that might also be related to the high root dry

weight, these roots might have supported the cold weather and sustained the plant

through the following months. Shokaeva (2008) reported that the effect of freeze on

yield can be correlated to plant growth and root damage. It is possible that 'Winter

Dawn' roots were less damaged after the freezing events. In terms of plant growth,

Macias-Rodriguez et al. (2002) reported that strawberry crowns are a high source of

soluble and storage carbohydrates, important for growth and fruit development. These

storage carbohydrates might have supported the plant growth and strawberry fruit

production after the cold weather in January and February. As Fernandez et al. (2001)

mentioned, after allocating their resources to roots, crowns, and leaves the strawberry

plant shift the resources to vegetative and reproductive plant parts. However, as a

consequence of the low temperatures, growing was not as fast as it should have been

or the plants did not grow enough to be able to storage an adequate amount of

carbohydrates to be shifted for fruit development. 'Florida Radiance' had the lowest root

and shoot dry weight regardless of irrigation program. Probably, as a result of those

values it had the lowest total yield. Nonetheless, it had the highest early yield of 2.72

t/ha which in terms of value represents more income for a strawberry grower than the

early yields of 'Winter Dawn' and 'Strawberry Festival'.

In general, pre-storage evaluation of strawberry fruits was not affected by irrigation

programs but it was affected by the cultivars during the second season. As mentioned

by Chandler (2009), the flavor of 'Winter Dawn' is slightly acidic, it had the highest









values of titratable acidity and generally the lowest values of soluble solids content

through the season in contrast with 'Strawberry Festival' that had lower titratable acidity

and higher values of soluble solids content. Fruit external color fruit was different among

cultivars in most of the evaluations, but it did not always follow the same order. 'Winter

Dawn' had the highest values of chroma at the end the season (17 and 20 WAT) in both

pre-storage and post-storage evaluations, meaning that 'Winter Dawn' fruit had a more

vivid color. The lower the hue angle the redder the strawberry fruit, and those low

values corresponded to 'Florida Radiance' most of the time in addition to low values of

lightness. In terms of quality the cultivars had on average similar values after one week

of storage at 7C except for the evaluation 17 WAT, where 'Winter Dawn' had the

lowest quality.

According to Florida Automatic Weather Network (2010), the average

evapotranspiration during the 2009-2010 strawberry season was 2.5 L/m/day, it was

lower than the 2008-2009 strawberry season. Probably the irrigation program of 1.8

L/m/day in one or two cycles/day provided enough water for growth and development of

the strawberry plants, without affecting nutrient absorption and postharvest quality, and

even with these irrigation programs soil water content was not lower than 10%, meaning

that the soil was on field capacity for the strawberry season. However, as discussed

before, the results obtained in the present research could have been strongly influenced

by the particular weather conditions. Further research needs to be done to corroborate if

an irrigation volume of 1.8 L/m/day can be enough to supply the water needs of the crop

without reducing growth, yield and postharvest quality.









Table 4-1. Average environmental conditions from October 2009 to March 2010 from
FAWN0 weather report for Balm, Florida.
Air Temperature Soil Temperature
(oC) (oC) R Relative Solar
Month ()) Rn humidity irradiation
Avg Min Max Avg Min Max (m (%) (w/m2)

October 24.3 7.5 37.4 25.3 21.7 27.8 35.6 79 187.5

November 19.1 4.6 29.5 22.2 18.0 25.9 46.5 80 156.6

December 16.7 -0.9 29.4 19.1 15.3 21.9 63.0 82 113.4

January 11.7 -4.5 28.0 15.4 10.6 19.2 81.1 76 145.3

February 12.1 -0.6 26.1 15.5 12.4 18.8 56.4 74 161.5

March 15.1 0.5 27.9 16.7 13.0 20.1 156.3 73 218.3


0Florida Automated Weather Network









Table 4-2. Effects of irrigation volumes and frequencies on strawberry plant diameter at
6, 14, and 17 weeks after transplant (WAT). 2009-10 Season.

Volume Frequency Plant Diameter (cm)

(L/m/day) (cycles/day) 6 WAT 14 WAT 17 WAT
1.8 24.3 31.1 28.3
3.6 1 23.3 31.8 29.7
5.4 22.4 30.6 27.9

1.8 23.0 31.2 29.7
3.6 2 24.2 31.6 29.4
5.4 22.7 31.6 29.6
Significance (P Cultivars
'Strawberry Festival' 22.8 33.8 c8 30.7 b
'Florida Radiance' 23.5 28.4 a 25.7 a
'Winter Dawn' 23.6 31.8 b 31.0 b
Significance (P
2Data examined with analysis of variance. Means followed by the same letter are not significantly different
within a column.
NS,* Not significant and significant at P<0.05, respectively.









Table 4-3. Effects of irrigation volumes and frequencies on strawberry leaf chlorophyll
content at 6, 14 and 17 weeks after transplant (WAT). 2008-09 Season.
Volume Frequency Chlorophyll content (SPAD value)

(L/m/day) (cycles/day) 6 WAT 14 WAT 17 WAT
1.8 44.2 47.5 45.6
3.6 1 43.9 47.3 46.2
5.4 44.6 46.9 44.8

1.8 44.3 47.3 46.4
3.6 2 44.9 47.3 46.2
5.4 43.9 48.2 45.4
Significance (P Cultivars
'Strawberry Festival' 41.0 a8 46.2 a 43.7 a
'Florida Radiance' 45.3 b 47.2 b 44.8 b
'Winter Dawn' 46.6 c 48.9 c 48.7 c
Significance (P
"Data examined with analysis of variance. Means followed by the same letter are not significantly different
within a column.
NS,* Not significant and significant at P<0.05, respectively.









Table 4-4. Effects of irrigation volumes and frequencies on strawberry root dry weight
at 22 weeks after transplant. 2009-10 Season.

Irrigation Programs

Volume Frequency Root dry weight

(L/m/day) (cycles/day) (g)

1.8 5.08

3.6 1 5.47

5.4 5.33

1.8 5.70
3.6 2 5.18

5.4 5.36

Significance (P
Cultivars

'Strawberry Festival' 5.55 b8

'Florida Radiance' 4.18 c

'Winter Dawn' 6.33 a

Significance (P
2Data examined with analysis of variance. Means followed by the same letter are not significantly different
within a column.
NS,* Not significant and significant at P<0.05, respectively.









Table 4-5. Effects of irrigation volumes and frequencies on strawberry shoot dry weight
at 22 weeks after transplant. 2009-10 Season.

Volume Frequency Shoot dry weight
Cultivar
(L/m/day) (cycles/day) (g)


'Strawberry Festival'










'Florida Radiance'


23.27 cde2

26.34 bcd

20.84 de

32.44 a

27.30 abc

22.63 cde

10.37 f

11.73f

11.51 f

13.34 f

10.12 f

10.52 f

23.42 cde

29.35 ab

20.81 de

20.47 e

22.73 cde

23.26 cde
*


'Winter Dawn'


Significance (P

2Data examined with analysis of variance. Means followed by the same letter are not significantly different
within a column.
NS,* Not significant and significant at P<0.05, respectively.









Table 4-6. Effects of irrigation volumes and frequencies on strawberry foliar nutrient concentration at 6 weeks after
transplant. 2009-10 Season.
Volume Frequency N P K Ca Mg S Fe Cu B Zn Mn

(L/m/day) (cycles/day) (%) (mg/L)

1.8 3.25 0.38 2.84 0.85 0.48 0.20 63.67 6.08 34.92 34.67 54.42

3.6 1 3.38 0.43 3.05 0.81 0.46 0.21 65.17 6.17 41.42 39.17 55.83

5.4 3.32 0.39 2.87 0.80 0.47 0.20 61.25 4.50 34.67 38.75 53.17

1.8 3.24 0.48 2.99 0.84 0.47 0.21 65.00 8.08 38.08 36.25 54.75

3.6 2 3.32 0.40 2.99 0.80 0.46 0.21 68.33 7.17 40.25 37.67 55.92

5.4 3.39 0.39 2.91 0.79 0.47 0.21 68.75 7.50 40.92 37.83 59.08

Significance (P
Cultivar

'Strawberry Festival' 3.10 b2 0.43 2.90 b 0.76 b 0.43 b 0.21 a 66.92 7.04 38.00 42.00 a 49.00 b

'Florida Radiance' 3.40 a 0.41 3.00 a 0.85 a 0.48 a 0.21 a 65.46 6.75 39.42 35.00 b 48.00 b

'Winter Dawn' 3.40 a 0.40 2.90 b 0.84 a 0.49 a 0.20 b 63.71 5.96 37.71 35.00 b 70.00 a

Significance (P
2Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column.
NS* Not significant and significant at P<0.05, respectively.










Table 4-7. Effects of irrigation volumes and frequencies on strawberry foliar nutrient concentration at 14 weeks after
transplant. 2009-10 Season.

Volume Frequency N P K Ca Mg S Fe Cu B Zn Mn

(L/m/day) (cycles/day) (%) (mg/L)

1.8 3.41 0.44 a 2.40 a 0.99 0.45 0.22 ab 68.42 8.75 46.00 a 28.92 89.00 a

3.6 1 3.45 0.42 a 2.40 ab 0.96 0.44 0.22 a 68.50 8.42 43.00 b 28.00 75.00 bc

5.4 3.21 0.40 b 2.10 c 1.00 0.46 0.21 c 68.75 8.33 38.00 d 29.58 80.00 ab

1.8 3.38 0.43 a 2.30 b 0.99 0.46 0.22 abc 67.25 8.42 45.00 a 28.00 75.00 bc

3.6 2 3.39 0.42 a 2.40 ab 0.97 0.44 0.22 a 66.75 8.25 43.00 b 27.17 69.00 c

5.4 3.39 0.42 a 2.40 ab 0.95 0.45 0.21 bc 66.25 8.08 40.00 c 27.17 84.00 ab

Significance (P<0.05) NS NS NS NS NS NS

Cultivar
3.20
'Strawberry Festival' c 0.44 a 2.30 b 0.90 b 0.43 c 0.22 b 67.00 c 8.40 a 47.00 a 30.00 a 84.00 b
ca
'Florida Radiance' 3.60 0.40 b 2.40 a 1.01 a 0.45 b 0.23 a 71.00 a 8.70 a 40.00 b 28.00 a 61.00 c
a
3.30
'Winter Dawn' 0.43 a 2.30 b 1.02 a 0.47 a 0.21 c 64.00 c 8.00 b 40.00 b 26.00 b 92.00 a
b
Significance (P<0.05) *

'Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column.
NS* Not significant and significant at P<0.05, respectively.










Table 4-8. Effects of irrigation volumes and frequencies on strawberry foliar nutrient concentration at 17 weeks after
transplant. 2009-10 Season.
Volume Frequency N P K Ca Mg S Fe Cu B Zn Mn

(L/m/day) (cycles/day) (%) (mg/L)

1.8 3.3 ab2 0.44 a 2.26 bc 0.97 0.40 0.21 a 65.95 9.22 46.00 a 26.00 ab 112.00 a

3.6 1 3.4 a 0.45 a 2.28 bc 1.04 0.41 0.21 a 73.05 9.23 47.00 a 27.00 a 101.00 ab

5.4 3.2 c 0.39 c 2.17 c 0.98 0.42 0.20 c 64.84 8.86 40.00 b 25.00 bc 90.00 bc

1.8 3.3 b 0.44 ab 2.32 ab 0.96 0.41 0.21 b 66.68 8.49 50.00 a 26.00 ab 95.00 abc

3.6 2 3.4 ab 0.44 a 2.36 ab 0.95 0.40 0.21 ab 69.10 8.95 47.00 a 24.00 bc 78.00 c

5.4 3.3 b 0.42 b 2.41 a 0.92 0.40 0.20 bc 66.31 8.37 40.00 b 24.00 c 92.00 bc

Significance (P<0.05) NS NS NS NS *

Cultivar

'Strawberry Festival' 3.10 c 0.40 b 2.20 c 0.86 c 0.37 c 0.20 b 64.00 b 8.40 b 51.00 a 26.00 a 101.00 a

'Florida Radiance' 3.50 a 0.40 b 2.40 a 1.08 a 0.41 b 0.22 a 75.00 a 9.80 a 42.00 b 27.00 a 71.00 b

'Winter Dawn' 3.3 Ob 0.50 a 2.30 b 0.97 b 0.44 a 0.20 b 65.00 b 8.20 b 41.00 b 24.00 b 112.00 a

Significance (P<0.05) *

2Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column.
NS* Not significant and significant at P<0.05, respectively.









Table 4-9. Effects of irrigation volumes and frequencies
at 14 weeks after transplant. 2009-10 Season.


on strawberry fruit quality pre-storage (8 days at 7C) evaluation


Vo e Fre y Total titratable Soluble solids E l
Volume Frequency ad External color
acidity content
(L/m/day) (cycles/day) (%) (oBrix) Lightness Chroma hue angle

1.8 1.31 7.69 35.79 40.00 28.87

3.6 1 1.32 8.44 35.75 40.06 29.47

5.4 1.33 7.49 35.93 40.97 28.83

1.8 1.30 8.01 35.50 39.73 28.45

3.6 2 1.31 7.65 36.07 40.01 29.21

5.4 1.31 7.89 35.02 39.21 27.51

Significance (P
Cultivar

'Strawberry Festival' 1.04 c 9.16 a 36.82 a 39.13 b 31.66 a

'Florida Radiance' 1.38 b 7.89 b 34.69 c 40.36 a 26.41 c

'Winter Dawn' 1.52 a 6.53 c 35.52 b 40.49 a 28.09 b

Significance (P
2Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column.
NS,* Not significant and significant at P<0.05, respectively.









Table 4-10. Effects of irrigation volumes and frequencies on strawberry fruit quality pre-storage (8 days
at 17 weeks after transplant. 2009-10 Season.


at 7C) evaluation


Vo e Fre y Total titratable Soluble solids E l
Volume Frequency ad External color
acidity content
(L/m/day) (cycles/day) (%) (oBrix) Lightness Chroma hue angle

1.8 1.13 7.03 35.57 41.67 28.88

3.6 1 1.10 6.71 35.62 41.51 29.27

5.4 1.06 7.13 35.85 41.55 29.45

1.8 1.11 6.94 34.96 41.21 27.99

3.6 2 1.10 7.02 35.17 41.59 28.92

5.4 1.13 6.86 35.40 41.19 29.19

Significance (P
Cultivar

'Strawberry Festival' 1.18 as 7.64 a 35.22 b 39.49 b 30.25 a

'Florida Radiance' 0.93 a 6.42 b 33.78 c 39.87 b 27.45 b

'Winter Dawn' 1.20 b 6.79 b 37.29 a 45.01 a 29.15 a

Significance (P
2Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column.
NS* Not significant and significant at P<0.05, respectively.









Table 4-11. Effects of irrigation volumes and frequencies on strawberry fruit quality pre-storage (8 days
at 20 weeks after transplant. 2009-10 Season.


at 7C) evaluation


Vo e Fre y Total titratable Soluble solids E l
Volume Frequency ad External color
acidity content
(L/m/day) (cycles/day) (%) (oBrix) Lightness Chroma hue angle

1.8 1.00 7.59 33.02 37.58 24.55

3.6 1 1.04 7.86 33.80 38.51 26.26

5.4 0.99 7.67 33.78 38.76 25.58

1.8 1.04 7.99 33.69 38.90 25.17

3.6 2 1.05 8.22 34.12 38.88 26.70

5.4 1.02 7.75 33.99 38.39 25.86

Significance (P
Cultivar

'Strawberry Festival' 1.07 a8 9.03 a 34.27 a 36.56 c 27.47 a

'Florida Radiance' 0.92 b 7.52 b 32.75 b 38.83 b 23.77 c

'Winter Dawn' 1.08 a 6.99 b 34.19 a 40.11 a 25.82 b

Significance (P
2Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column.
NS* Not significant and significant at P<0.05, respectively.









Table 4-12. Effects of irrigation volumes and frequencies on strawberry fruit quality post-storage (8 days at 7C)
evaluation at 14 weeks after transplant. 2009-2010 Season.
Soluble
Total titratable
Volume Frequency acitsolids External color
acidity content Visual quality

(L/m/day) (cycles/day) (%) (oBrix) Lightness Chroma hue angle

1.8 1.30 6.79 33.24 40.32 28.46 6.64

3.6 1 1.32 6.73 33.80 40.98 29.65 6.96

5.4 1.26 7.11 33.11 40.60 27.64 6.82

1.8 1.31 7.12 34.02 39.66 28.37 6.65

3.6 2 1.33 6.88 33.63 40.24 28.76 6.56

5.4 1.30 6.82 32.93 39.95 27.11 6.18

Significance (P
Cultivar

'Strawberry Festival' 1.37 b2 7.95 a 34.32 a 38.31 b 29.98 a 6.58

'Florida Radiance' 1.04 c 6.44 b 32.91 b 41.31 a 26.64 c 6.83

'Winter Dawn' 1.50 a 6.32 b 33.13 b 41.25 a 28.37 b 6.50

Significance (P
2Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column.
NS* Not significant and significant at P<0.05, respectively.









Table 4-13. Effects of irrigation volumes and frequencies on strawberry fruit quality post-storage (8 days at 7C)
evaluation at 17 weeks after transplant. 2009-2010 Season.
Vo e Fre y Total titratable Soluble solids
Volume Frequencycontent External color
acidity content Visual quality
Visual quality
(L/m/day) (cycles/day) (%) (oBrix) Lightness hue angle

1.8 1.15 8.29 33.73 ab 26.01 abc 6.11

3.6 1 1.11 8.53 33.10 ab 25.72 bc 6.45

5.4 1.14 8.41 33.64 ab 26.66 ab 6.03

1.8 1.13 8.52 32.90 b 25.28 c 5.85

3.6 2 1.17 8.36 34.03 a 26.87 a 6.56

5.4 1.19 8.64 32.83 b 25.35 c 5.84

Significance (P
Cultivar

'Strawberry Festival' 1.19 a8 9.32 a 33.69 a 28.29 a 6.74 a

'Florida Radiance' 1.03 b 7.98 b 31.63 c 24.07 c 6.46 a

'Winter Dawn' 1.23 a 8.07 b 34.80 a 25.59 b 5.22 b

Significance (P
2Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column.
NS* Not significant and significant at P<0.05, respectively.









Table 4-14. Effects of irrigation volumes and frequencies on strawberry chroma post-
storage (8 days at 7C) at 17 weeks after transplant 2009-10 Season.

Volume Frequency
Cultivar Chroma
(L/m/day) (cycles/day)

1.8 36.75 d2

3.6 1 37.36 cd

54 37.13 cd
'Strawberry Festival' 5.4 37.13 cd
1.8 37.06 d

3.6 2 36.52 d

5.4 37.35 cd

1.8 35.86 d

3.6 1 36.09 d

'Florida Radiance' 5.4 37.58 cd
1.8 37.67 cd

3.6 2 39.70 bc

5.4 37.15 cd

1.8 43.06 a

3.6 1 41.01 ab

'Winter Dawn' 5.4 41.73 ab
1.8 39.67 bc

3.6 2 42.72 a

5.4 41.25 ab
Significance (P
2Data examined with analysis of variance. Means followed by the same letter are not significantly different
within a column.
NS,* Not significant and significant at P<0.05, respectively.


100









Table 4-15. Effects of irrigation volumes and frequencies on strawberry fruit quality post-storage (8 days at 7C)
evaluation at 20 weeks after transplant. 2009-2010 Season.
Total Soluble
Volume Frequency titratable solids External color Visual
acidity content quality
(L/m/day) (cycles/day) (%) (oBrix) Lightness Chroma hue angle

1.8 0.99 8.09 31.37 37.89 23.95 7.58 a

3.6 1 1.03 8.00 31.65 38.77 25.47 6.82 bc

5.4 1.00 8.38 31.99 39.16 25.32 6.94 abc

1.8 1.03 8.41 32.87 39.45 25.93 6.78 bc

3.6 2 1.01 8.09 33.08 38.74 26.41 6.36 c

5.4 0.97 8.50 31.89 38.51 25.47 7.36 ab

Significance (P
Cultivar

'Strawberry Festival' 1.05 as 9.24 a 32.87 a 37.62 b 27.72 a 6.92

'Florida Radiance' 0.89 b 7.88 b 31.07 a 38.50 b 22.97 c 6.97

'Winter Dawn' 1.08 a 7.61 b 32.48 b 40.14 a 25.60 b 7.02

Significance (P
2Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column.
NS* Not significant and significant at P<0.05, respectively.









Table 4-16. Effects of irrigation volumes and frequencies on strawberry early and total
yield. 2009-10 Season.
Irrigation Programs
Early Yield Total Yield
Volume Frequency

(L/m/day) (cycles/day) (ton/ha) (ton/ha)

1.8 2.32 10.64

3.6 1 2.43 11.12

5.4 2.31 10.30

1.8 2.39 10.42
3.6 2 2.52 11.30

5.4 2.28 10.74

Significance (P<0.05) NS NS

Cultivars

'Strawberry Festival' 2.26 b8 10.13 b

'Florida Radiance' 2.72 a 8.73 c

'Winter Dawn' 2.14 c 13.40 a

Significance (P
2Data examined with analysis of variance. Means followed by the same letter are not significantly different
within a column.
NS,* Not significant and significant at P<0.05, respectively.


102
















14


12


a 10
-4-- 100 gal100 ft/cycle 1 cycle
100 gal/100 ft/week 2 cycles
o( -A- 300 gal/l00 ft/week 1 cycle
-- 300 gal/100 ft/week 2 cycles
6- 200 gal/100 ft/week 1 cycle
-- 200 gal/100 ft/week 2 cycles


4
7 9 13 15 17 19

Weeks after transplant

Figure 4-1. Effects of irrigation volumes and frequencies on soil water content (%).
2009-10 Strawberry Season.


103









CHAPTER 5
SUMMARY AND CONCLUSIONS

The use of specific irrigation programs for the most planted UF cultivars may

optimize strawberry production and water conservation in west central Florida. The

proposed irrigation programs for these cultivars were tested during the strawberry

seasons 2008-09 and 2009-10. The programs included irrigation volumes of 1.8, 3.6

and 5.4 L/m/day and two frequencies one and two cycles per day. The first strawberry

season, the early yield of 'Strawberry Festival' was not affected by irrigation programs, it

ranged between 7.8 and 9.0 t/ha. For total yields there were no effects when the

irrigation programs were applied in a frequency of one cycle per day. However, when

irrigation volumes were applied twice per day there was an effect on total yields. The

lowest total yield was found in plots irrigated twice per day with 1.8 L/m/day, whereas

the highest fruit yields were obtained in plots irrigated with either 3.6 or 5.4 L/m/day,

ranging between 29.6 and 30.0 t/ha. This result suggests that applying 3.6 L/m/day can

be enough water to satisfy the strawberry water needs and the irrigation system

requirements. Applying more water volume than 3.6 L/m/day can result in waste of

water and nutrient leaching.

Plant growth was affected at the end of the season by the irrigation frequency of

two cycles per day, with higher water volume resulting in higher plant diameter. Shoot

dry weight at the end of the season had a similar pattern, 5.4 L/m/day resulted in the

highest shoot dry weight for both irrigation frequencies with a stronger effect when the

water volume was applied in one cycle/day. Similar results were found by Kirnak et al.

(2003) with higher shoot dry weight when the plants were irrigated with the higher

volume evaluated. Both plant diameter and shoot dry weight had the lowest values


104









when 1.8 L/m/day was applied in two cycles per day. That response was most likely

because of the high evapotranspiration, air and soil temperature and solar irradiation in

west central Florida at the end of the strawberry season (March and April 2009).

Transpiration increases because there is a bigger plant canopy, as a result the crop

water requirements increase and 1.8 L/m/day cannot cover those plant requirements.

An irrigation volume of 3.6 L/m/day (average evapotranspiration in west central Florida)

can supply the strawberry needs, this result is similar to what Gutal et al. (2005) found

in strawberry irrigation when irrigating at alternate days 85% of two days pan

evaporation gave higher yields and higher water use efficiency Nutritional status of the

plants through the season was within the adequate ranges for the nutrients evaluated,

N, P, K, Ca, Mg, S, Fe, Mn, Zn, B, and Cu.

In terms of postharvest quality, water volumes affected the strawberry fruit

firmness at 14 WAT when the program was 1.8 L/m/day in one cycle per day. There

was an effect of water volume applied in one cycle per day on total titratable acidity; it

was higher when the smallest water volume (1.8 L/m/day) was applied at the end of the

season. This irrigation program had also the highest lightness among treatments. The

irrigation programs (volumes and frequencies) had no effect on soluble solids content.

Contrary to the results of this research Ostrowska and Chelpiriski (2003) found no effect

of irrigation on fruit acidity but the total sugar content was lower in irrigated treatments

for the cultivars evaluated. It was demonstrated that applying and irrigation volume of

5.4 L/m/day or more per season did not increase strawberry yields, but did increase the

water waste and leaching, while 1.8 L/m/day during the whole season resulted in plant

growth and total yield reduction. For 'Strawberry Festival' an irrigation volume of 3.6


105









L/m/day in one or two cycles per day resulted in higher total yields than 1.8 L/m/day,

especially for the frequency of two cycles per day. Irrigation should occur only once per

day when low water volumes are utilized. The irrigation volume of 1.8 L/m/day in one or

two cycles per day can be use for 'Strawberry Festival' at the beginning of the season

(first 8 weeks) when plant size is still small and then the volume can be increased to 3.6

L/m/day when the size of the plants gets bigger and the water needs increase.

The second season the cultivars evaluated were 'Strawberry Festival', 'Florida

Radiance' and 'Winter Dawn'. The weather conditions included low air and soil

temperatures and low irradiation; there were fourteen days of temperatures below 0C

and approximately 24 days under freeze protection during the whole season, an

unusual cold winter in west central Florida. For early and total yield there were no

significant differences among the irrigation programs and there was no interaction

between the irrigation programs and the cultivars. For early yields the range was

between 2.31 and 2.52 t/ha while the total yields ranged from 10.30 to 11.30 t/ha. There

was a cultivar effect for both early and total yield. The highest early yield was obtained

by 'Florida Radiance', followed by 'Strawberry Festival' and 'Winter Dawn'. "Winter

Dawn' had the highest total yield of 13.40 t/ha for the season 2009-10. 'Strawberry

Festival' had a total yield of 10.13 t/ha and 'Florida Radiance' had the lowest total yield,

8.73 t/ha. Plant growth variables such as plant diameter and chlorophyll content of the

strawberry plants were not affected by the irrigation programs, there was not interaction

irrigation program x cultivar but there were differences between cultivars. All nutrients

were in adequate range through the season, Whitty et al. (2002) mentioned that nutrient

utilization and fertilization practices are influenced by the moisture status of the crop


106









plants; even the lowest water volume of 1.8 L/m/day allowed the soil to have an

appropriate water status so the plant nutrients were available and leaching can be

reduced. There were no significant differences among irrigation programs for root dry

weight, ranging from 4.05 to 5.24 g, but there were differences among the strawberry

cultivars. 'Winter Dawn' had the highest root dry weight followed by 'Strawberry Festival'

and 'Florida Radiance'.

There were effects of the irrigation program x cultivar for shoot dry weight.

'Strawberry Festival' had the highest shoot dry weight from plots irrigated with 1.8

L/m/day in two cycles per day, while the lowest values were for 'Florida Radiance' in all

the irrigation programs. The soil water content was at field capacity the entire season,

between 10% and 14%, even for the water volume of 1.8 L/m/day applied in one or two

cycles per day. As a result the plants from all the plots had enough available water to

supply crop water needs, since the temperatures were low the metabolic rate of those

plants was probably not as high as the first season. The fact that 'Winter Dawn' had the

highest total yield might be related to the high dry root weight; these roots supported the

cold weather and sustained the plant through the following months. 'Florida Radiance'

had the lowest root and shoot dry weight regardless of irrigation program and probably

as a result of those values it had the lowest total yield. However, it had the highest early

yield of 2.72 t/ha which represents more income for a strawberry grower than the early

yields of 'Winter Dawn' and 'Strawberry Festival'.

There were no significant differences on total titratable acidity, soluble solids

content and external color expressed as lightness, chroma and hue angle among

irrigation programs in any of the pre-storage evaluations. Kays (1999) mentioned that in


107









horticultural crops, changes in water status can alter the general condition of the

produce by decreasing quality and product weight. However, the strawberry fruit quality

from all the irrigated plots was not affected by the water status, which meant that the

lowest volume provide enough water without affecting the postharvest quality. There

was no interaction irrigation program x cultivar but there were differences among

cultivars. "Winter Dawn' usually had the highest total titratable acidity and the lowest

soluble solids content, but it had higher chroma meaning a more vivid external color.

The post-storage analysis included total titratable acidity, soluble solids content,

external color (lightness, chroma and hue angle) and visual quality. There were no

significant differences among irrigation programs for any of the variables evaluated

except for hue angle at 17 WAT and visual quality at the end of the season, where the

lowest volume applied in one cycle/day had the highest fruit visual quality inside the

clamshell. Visual quality was different among cultivar only at 17 WAT, 'Winter Dawn'

had a slightly lower value than 'Strawberry Festival' and 'Florida Radiance'.

According to Florida Automatic Weather Network (2010), average

evapotranspiration during the 2009-2010 strawberry season (October 15, 2009 March

30, 2010) was 2.36 L/m/day; it was lower than the 2.54 L/m/day obtained in 2008-2009

strawberry season (October 15, 2008-March 30, 2009). This difference might have

influenced the results during the second season. The 'Strawberry Festival' plant

diameters obtained the second season were much smaller than the ones obtained the

first season, this small plant growth through the season had an impact on strawberry

yield, and it is very likely that the other two cultivars had the same effect on growth..

Probably as a result of the low air and soil temperature, the low irradiation and the


108









reduced transpiring surface area, the plants did not transpire as much as in a warmer

season. In adittion to low evapotranspiration, the large amount of days that the plants

were under freeze protection might also have reduced the growth rate. Other

consequences of this weather conditions were hundreds of gallons of water spent in

freeze protection.

Satisfying crop water needs with as minimum leaching as possible is one of the

goals of irrigation scheduling. The results of this research showed that every season

performed different. In the first season irrigation programs had an influence on

strawberry growth with larger plant diameter and shoot dry weight for the highest

irrigation volume, higher marketable yield when a volume on 3.6 L/m/day was applied

with much better results when the frequency of two cycles per day was used and

postharvest quality including an increased on firmness as the water volume increased

and higher total titratable acidity using the lowest volume of 1.8 L/m/day while the

second season there was no influenced of the irrigation programs and it had more

cultivar dependent results. In a strawberry season with weather conditions as the 2008-

09 strawberry season a volume of 1.8 L/m/day can be used the first eight weeks and

then the volume can be increased to 3.6 L/m/day to cover the water needs with better

results when the frequency of two cycles per day is used. Reducing the irrigation

volume from 5.4 L/m/day to the program described above strawberry growers could

save around 11 million m3 of water per 24-week season for the Florida strawberry

industry as a whole without causing plant stress and yield reduction, excessive

leaching, and saving energy for pumping.


109









Based on the obtained results we can conclude that irrigation programs, and the

interaction between irrigation programs and cultivars had an effect on strawberry

growth, yield and fruit quality in west central Florida, so the null hypotheses can be

rejected. However, additional research needs to be conducted to confirm that irrigation

volumes between 1.8 L/m/day and 3.6 L/m/day in one or two cycles per day can satisfy

strawberry water requirements on sandy soils in west central Florida without reducing

plant growth, marketable yield and postharvest quality.


110









APPENDIX
TEMPERATURE DATA FROM FAWN WEATHER REPORT FOR BALM,
FLORIDA DURING 2008-09 AND 2009-10 STRAWBERRY SEASONS

Table A-1. Daily average of data from FAWN0 weather report taken at 60 cm from soil
from October 2008 to March 2009, Balm, FL.
Season 2008-2009
Date Average Minimum Maximum ETo
(C) (L/m/day)


15-Oct-08
16-Oct-08
17-Oct-08
18-Oct-08
19-Oct-08
20-Oct-08
21-Oct-08
22-Oct-08
23-Oct-08
24-Oct-08
25-Oct-08
26-Oct-08
27-Oct-08
28-Oct-08
29-Oct-08
30-Oct-08
31-Oct-08
1-Nov-08
2-Nov-08
3-Nov-08
4-Nov-08
5-Nov-08
6-Nov-08
7-Nov-08
8-Nov-08
9-Nov-08
10-Nov-08
11-Nov-08
12-Nov-08


24.0
23.2
23.4
22.9
20.0
21.1
21.7
22.8
24.0
23.5
23.8
19.4
18.8
12.0
11.0
14.6
18.3
18.4
19.4
21.0
18.2
17.7
19.1
19.8
19.9
17.1
16.4
19.3
23.3


17.7
17.8
16.6
16.1
13.3
15.4
16.0
17.0
21.0
20.7
18.8
13.0
10.7
6.0
1.6
5.0
12.3
13.8
17.4
17.0
16.5
16.0
12.7
12.0
12.4
10.0
8.2
11.5
17.6


31.0
31.0
32.2
29.7
27.5
29.2
29.3
28.8
28.5
27.6
28.4
27.2
27.6
18.1
20.1
24.0
26.3
25.5
25.7
28.0
20.2
19.4
27.5
29.1
27.3
25.4
25.6
28.2
30.7


3.8
3.8
3.8
3.5
3.5
3.5
3.5
3.5
3.1
2.5
2.2
3.1
3.1
2.8
2.2
2.2
2.5
2.8
2.5
2.2
2.8
1.6
1.6
2.5
2.5
2.5
2.5
2.2


111









Table A-1. Continued
Season 2008-2009
Date Average Minimum Maximum ETo
(C) (L/m/day)
13-Nov-08 25.1 20.6 31.9 2.5
14-Nov-08 24.5 19.7 32.2 2.8
15-Nov-08 22.7 17.9 27.6 3.1
16-Nov-08 12.4 3.2 17.9 2.8
17-Nov-08 11.0 2.6 20.3 2.2
18-Nov-08 13.3 6.8 21.9 1.9
19-Nov-08 9.4 2.2 18.6 1.6
20-Nov-08 10.9 0.8 21.4 1.9
21-Nov-08 14.1 6.1 23.8 1.6
22-Nov-08 11.8 4.5 21.2 1.6
23-Nov-08 13.9 7.4 23.2 1.9
24-Nov-08 16.1 9.6 25.6 1.9
25-Nov-08 15.0 7.8 23.9 1.9
26-Nov-08 12.4 2.8 23.0 1.9
27-Nov-08 11.1 0.6 23.4 1.9
28-Nov-08 13.4 3.3 26.3 1.6
29-Nov-08 17.3 6.4 27.4 1.6
30-Nov-08 18.6 15.2 25.2 1.9
1-Dec-08 16.5 11.9 20.6 2.2
2-Dec-08 11.7 2.1 17.0 1.9
3-Dec-08 11.0 1.3 21.7 1.9
4-Dec-08 16.2 8.8 26.0 1.3
5-Dec-08 16.7 8.1 26.5 1.6
6-Dec-08 17.2 9.3 24.4 1.9
7-Dec-08 14.2 6.2 19.9 1.9
8-Dec-08 13.4 3.0 24.5 1.9
9-Dec-08 19.3 10.3 28.1 1.6
10-Dec-08 22.5 18.8 29.4 1.6
11-Dec-08 19.9 16.5 22.3 2.2
12-Dec-08 14.4 8.2 18.3 2.2
13-Dec-08 11.7 3.0 20.4 1.6
14-Dec-08 17.8 10.9 25.5 1.6
15-Dec-08 20.2 17.8 25.1 1.3
16-Dec-08 19.9 13.6 27.4 1.9
17-Dec-08 20.5 14.6 27.6 1.6


112









Table A-1. Continued
Season 2008-2009
Date Average Minimum Maximum ETo
(C) (L/m/day)
18-Dec-08 20.2 14.7 27.6 1.9
19-Dec-08 18.7 12.5 27.5 1.9
20-Dec-08 16.7 11.0 25.2 1.9
21-Dec-08 17.5 9.6 26.1 1.9
22-Dec-08 12.6 6.7 17.3 1.6
23-Dec-08 15.1 6.1 24.8 1.9
24-Dec-08 21.6 15.2 28.2 1.3
25-Dec-08 22.7 20.1 27.5 1.9
26-Dec-08 21.9 17.1 28.7 2.2
27-Dec-08 20.2 14.4 27.7 1.9
28-Dec-08 19.9 13.2 28.1 2.5
29-Dec-08 19.4 12.4 26.9 2.2
30-Dec-08 18.0 7.4 26.0 1.9
31-Dec-08 15.0 5.4 24.2 1.9
1-Jan-09 15.3 8.4 22.9 1.9
2-Jan-09 17.9 12.8 26.3 1.6
3-Jan-09 18.1 11.1 26.0 1.9
4-Jan-09 19.5 13.1 27.5 1.9
5-Jan-09 19.7 13.8 29.3 1.9
6-Jan-09 20.2 12.7 28.7 1.9
7-Jan-09 18.1 6.8 24.9 2.2
8-Jan-09 13.3 4.0 22.1 2.2
9-Jan-09 13.7 6.3 24.1 2.2
10-Jan-09 15.8 7.5 26.7 1.6
11-Jan-09 17.6 9.5 26.2 1.6
12-Jan-09 17.7 15.2 20.8 1.9
13-Jan-09 15.7 10.3 25.9 1.9
14-Jan-09 11.2 1.7 21.2 1.6
15-Jan-09 8.5 2.3 15.4 2.2
16-Jan-09 10.0 4.7 17.5 1.6
17-Jan-09 9.3 1.6 19.0 1.6
18-Jan-09 12.3 2.6 22.6 1.6
19-Jan-09 16.7 10.0 20.8 1.6
20-Jan-09 11.3 5.1 17.6 1.9
21-Jan-09 4.2 -3.3 11.1 1.9


113









Table A-1. Continued
Season 2008-2009
Date Average Minimum Maximum ETo
(C) (L/m/day)
22-Jan-09 5.5 -4.7 18.1 1.9
23-Jan-09 9.8 -2.1 23.0 1.3
24-Jan-09 12.7 2.4 22.7 1.6
25-Jan-09 15.5 5.6 26.3 1.9
26-Jan-09 18.2 9.0 27.5 1.9
27-Jan-09 20.2 13.2 28.2 2.2
28-Jan-09 21.4 16.8 28.6 2.5
29-Jan-09 21.0 16.7 27.1 2.5
30-Jan-09 14.1 8.8 18.8 2.8
31-Jan-09 8.9 1.7 17.6 2.5
1-Feb-09 11.8 1.4 21.3 1.9
2-Feb-09 16.0 11.8 19.4 1.9
3-Feb-09 12.2 3.0 15.8 2.2
4-Feb-09 7.4 1.1 13.6 1.9
5-Feb-09 3.8 -2.7 12.6 2.2
6-Feb-09 8.7 -1.4 20.3 1.9
7-Feb-09 12.7 4.6 22.6 1.9
8-Feb-09 14.8 6.7 24.4 2.2
9-Feb-09 15.5 5.4 25.4 2.5
10-Feb-09 17.5 9.0 27.6 2.8
11-Feb-09 20.3 11.9 29.2 2.8
12-Feb-09 20.4 16.6 26.8 3.1
13-Feb-09 19.9 12.8 29.8 3.5
14-Feb-09 17.3 9.8 24.9 2.8
15-Feb-09 20.2 15.8 26.7 3.5
16-Feb-09 18.4 8.9 24.3 3.1
17-Feb-09 14.1 5.6 24.1 2.8
18-Feb-09 17.0 7.5 24.9 3.1
19-Feb-09 18.1 15.1 24.3 3.1
20-Feb-09 12.5 3.2 18.7 3.5
21-Feb-09 12.0 -0.2 24.5 2.5
22-Feb-09 16.3 7.7 24.7 2.8
23-Feb-09 15.4 8.7 23.6 2.8
24-Feb-09 14.5 5.0 24.8 2.8
25-Feb-09 17.0 9.9 25.6 3.1


114









Table A-1. Continued
Season 2008-2009
Date Average Minimum Maximum ETo
(C) (L/m/day)
26-Feb-09 17.0 8.6 25.9 3.1
27-Feb-09 18.0 9.8 28.4 3.1
28-Feb-09 19.0 9.8 28.6 3.5
1-Mar-09 15.0 10.1 20.1 3.5
2-Mar-09 10.0 2.4 14.8 3.8
3-Mar-09 9.5 1.0 19.2 2.5
4-Mar-09 12.6 3.1 23.2 2.8
5-Mar-09 16.2 7.4 25.1 2.8
6-Mar-09 17.4 7.9 27.0 3.1
7-Mar-09 17.9 8.1 28.5 3.5
8-Mar-09 18.8 8.8 28.5 3.5
9-Mar-09 19.4 9.8 28.7 3.5
10-Mar-09 19.8 10.1 30.9 3.8
11-Mar-09 20.3 10.0 31.5 3.8
12-Mar-09 20.1 11.0 29.9 4.1
13-Mar-09 21.6 14.5 29.2 3.8
14-Mar-09 21.9 15.4 30.5 3.8
15-Mar-09 22.5 15.9 30.9 3.5
16-Mar-09 22.2 15.0 30.0 4.1
17-Mar-09 20.6 14.7 26.8 4.1
18-Mar-09 21.6 16.6 28.8 4.1
19-Mar-09 21.1 15.2 28.8 2.8
20-Mar-09 20.2 11.2 28.8 4.4
21-Mar-09 19.6 13.2 27.9 4.1
22-Mar-09 17.7 11.1 25.1 4.1
23-Mar-09 17.1 14.0 21.0 3.8
24-Mar-09 19.3 10.7 27.9 3.8
25-Mar-09 20.1 11.0 28.5 2.5
26-Mar-09 21.6 14.7 29.8 4.1
27-Mar-09 22.3 16.1 30.2 4.4
28-Mar-09 25.2 20.6 31.7 4.7
29-Mar-09 20.5 11.2 24.5 4.1
30-Mar-09 18.7 7.4 30.1 5.0

0 Florida Automated Weather Network
* Daily averages of Penman-method Evapotranspiration.


115









Table A-2. Daily average of data from FAWN0 weather report taken at 60 cm from soil
from October 2009 to March 2010, Balm, FL.
Season 2009-2010
Date Average Minimum Maximum ETo
(C) (L/m/day)


15-Oct-09
16-Oct-09
17-Oct-09
18-Oct-09
19-Oct-09
20-Oct-09
21-Oct-09
22-Oct-09
23-Oct-09
24-Oct-09
25-Oct-09
26-Oct-09
27-Oct-09
28-Oct-09
29-Oct-09
30-Oct-09
31-Oct-09
1-Nov-09
2-Nov-09
3-Nov-09
4-Nov-09
5-Nov-09
6-Nov-09
7-Nov-09
8-Nov-09
9-Nov-09
10-Nov-09
11-Nov-09
12-Nov-09
13-Nov-09
14-Nov-09
15-Nov-09
16-Nov-09
17-Nov-09


26.1
24.6
18.9
13.4
15.5
20.2
22.5
23.3
24.5
23.1
20.5
23.2
25.5
25.9
26.0
25.3
24.7
23.6
21.7
21.0
22.8
20.6
18.7
20.2
21.4
23.2
23.2
21.6
15.6
15.9
17.9
16.8
17.7
18.6


21.1
23.3
11.5
8.5
7.5
13.3
16.7
19.5
19.7
18.0
15.4
12.8
22.1
22.2
21.2
20.5
20.5
18.8
16.1
18.1
17.9
14.5
12.0
14.6
15.9
20.4
20.7
18.8
11.9
8.5
11.2
9.3
9.8
12.6


31.5
26.9
23.7
19.3
24.2
27.7
29.5
28.2
32.4
29.6
28.5
32.5
31.6
36.2
32.6
31.7
31.0
28.6
29.5
25.8
29.3
26.4
26.2
27.1
27.4
27.4
27.3
25.4
18.9
22.5
24.8
24.9
26.6
26.9


3.8
2.2
2.8
2.5
2.8
3.1
3.5
3.5
3.5
3.5
3.1
3.1
2.8
3.1
4.1
3.8
3.5
3.5
3.1
2.8
3.1
3.1
2.8
3.1
2.8
2.2
2.2
2.5
1.9
2.2
2.5
2.2
2.5
2.5


116









Table A-2. Continued
Season 2009-2010
Date Average Minimum Maximum ETo
(C) (L/m/day)
18-Nov-09 20.0 12.4 28.3 2.5
19-Nov-09 19.3 14.1 25.9 2.5
20-Nov-09 18.6 13.0 26.1 2.2
21-Nov-09 20.7 15.8 27.7 2.5
22-Nov-09 22.2 18.4 26.9 2.2
23-Nov-09 21.9 17.8 28.2 2.5
24-Nov-09 21.4 17.7 27.0 2.2
25-Nov-09 19.3 16.7 20.3 1.3
26-Nov-09 16.3 8.0 21.0 1.9
27-Nov-09 10.8 5.0 17.9 1.6
28-Nov-09 10.7 4.6 18.6 1.6
29-Nov-09 14.7 5.8 24.5 1.9
30-Nov-09 16.9 8.4 25.5 1.9
1-Dec-09 20.0 14.0 27.5 2.2
2-Dec-09 22.7 17.7 28.0 2.5
3-Dec-09 20.4 15.9 24.0 1.9
4-Dec-09 14.2 12.8 16.4 1.3
5-Dec-09 13.6 8.3 16.5 1.6
6-Dec-09 11.9 4.9 19.5 1.6
7-Dec-09 19.5 14.5 24.6 1.9
8-Dec-09 21.5 18.7 26.4 2.2
9-Dec-09 23.5 18.7 28.3 2.5
10-Dec-09 19.6 14.7 24.7 1.9
11-Dec-09 14.0 11.5 17.5 1.6
12-Dec-09 20.3 14.0 25.8 1.9
13-Dec-09 21.9 16.2 29.0 2.2
14-Dec-09 21.8 16.6 29.0 2.2
15-Dec-09 22.0 16.0 29.4 2.2
16-Dec-09 19.7 15.7 25.6 1.9
17-Dec-09 18.9 15.3 22.7 1.9
18-Dec-09 20.0 16.4 22.7 1.6
19-Dec-09 14.8 12.0 18.3 1.6
20-Dec-09 10.8 5.4 16.0 1.3
21-Dec-09 8.5 1.5 16.7 1.3
22-Dec-09 10.2 3.3 18.7 1.6


117









Table A-2. Continued
Season 2009-2010
Date Average Minimum Maximum ETo
(C) (L/m/day)
23-Dec-09 15.1 7.6 21.7 1.6
24-Dec-09 18.7 10.9 25.2 1.9
25-Dec-09 19.4 12.2 23.8 1.9
26-Dec-09 13.6 9.3 18.2 1.3
27-Dec-09 11.0 7.6 15.1 1.3
28-Dec-09 12.2 5.6 19.4 1.3
29-Dec-09 7.7 -0.9 17.0 1.3
30-Dec-09 13.0 3.1 23.6 1.6
31-Dec-09 17.5 11.0 24.4 1.9
1-Jan-10 15.4 9.4 19.5 1.6
2-Jan-10 8.3 2.6 14.9 1.3
3-Jan-10 4.2 0.7 7.6 0.9
4-Jan-10 4.2 -2.1 11.7 0.9
5-Jan-10 4.1 -2.4 8.6 0.9
6-Jan-10 3.0 -3.3 11.0 0.9
7-Jan-10 5.7 -3.0 16.9 0.9
8-Jan-10 8.2 -0.7 16.9 1.9
9-Jan-10 1.6 -1.5 5.1 1.3
10-Jan-10 0.9 -3.4 6.7 0.9
11-Jan-10 2.7 -3.9 11.7 0.9
12-Jan-10 5.0 -4.5 15.0 0.9
13-Jan-10 7.3 -1.4 17.6 1.3
14-Jan-10 12.2 3.3 22.2 1.6
15-Jan-10 16.7 9.0 25.3 1.9
16-Jan-10 20.4 16.2 24.9 2.2
17-Jan-10 19.3 14.5 23.2 2.2
18-Jan-10 13.2 6.6 18.0 1.6
19-Jan-10 13.3 5.4 21.9 1.6
20-Jan-10 14.7 6.1 23.8 1.9
21-Jan-10 20.6 13.7 27.0 2.5
22-Jan-10 20.7 15.5 23.9 1.9
23-Jan-10 18.8 12.3 26.1 2.5
24-Jan-10 21.9 17.5 28.0 2.5
25-Jan-10 17.4 7.2 23.4 2.5
26-Jan-10 11.5 3.7 19.7 1.9


118









Table A-2. Continued
Season 2009-2010
Date Average Minimum Maximum ETo
(C) (L/m/day)
27-Jan-10 11.2 3.8 20.4 1.9
28-Jan-10 13.8 5.5 23.4 2.2
29-Jan-10 16.4 9.6 24.2 2.2
30-Jan-10 18.5 13.9 24.8 2.2
31-Jan-10 12.3 8.7 15.3 1.9
1-Feb-10 14.0 9.0 17.6 1.9
2-Feb-10 16.9 12.1 21.3 1.9
3-Feb-10 12.8 8.7 19.1 2.2
4-Feb-10 16.8 9.6 25.0 2.8
5-Feb-10 19.3 16.0 24.9 2.2
6-Feb-10 15.2 11.1 18.4 2.2
7-Feb-10 10.1 4.4 13.7 1.9
8-Feb-10 9.9 2.7 19.2 2.2
9-Feb-10 15.4 8.3 21.5 2.2
10-Feb-10 10.2 5.2 15.2 2.5
11-Feb-10 7.7 2.0 14.7 1.9
12-Feb-10 9.3 7.1 11.7 1.3
13-Feb-10 7.6 1.5 12.0 1.9
14-Feb-10 7.2 -0.1 16.4 2.2
15-Feb-10 11.1 -0.3 21.6 2.8
16-Feb-10 9.6 3.2 12.7 2.2
17-Feb-10 8.3 1.5 13.6 2.2
18-Feb-10 8.0 0.8 14.5 2.2
19-Feb-10 10.9 2.9 18.2 2.2
20-Feb-10 14.2 7.8 22.4 2.8
21-Feb-10 16.4 6.9 26.1 3.1
22-Feb-10 19.1 13.1 25.4 2.8
23-Feb-10 19.9 14.0 25.9 3.1
24-Feb-10 14.6 10.3 22.2 2.2
25-Feb-10 8.4 1.8 13.6 2.5
26-Feb-10 7.4 -0.6 17.1 2.5
27-Feb-10 7.6 0.9 13.4 1.9
28-Feb-10 10.4 1.9 16.9 2.8
1-Mar-10 11.1 0.5 21.9 2.8
2-Mar-10 14.9 7.1 21.4 2.8


119









Table A-2. Continued
Season 2009-2010
Date Average Minimum Maximum ETo
(C) (L/m/day)
3-Mar-10 10.3 7.7 13.4 2.2
4-Mar-10 8.6 0.5 13.0 2.5
5-Mar-10 8.7 0.9 16.6 2.8
6-Mar-10 10.3 2.0 19.5 2.8
7-Mar-10 11.3 1.5 21.7 3.1
8-Mar-10 13.0 3.2 23.6 3.1
9-Mar-10 15.1 8.8 23.2 2.8
10-Mar-10 18.1 8.4 27.9 3.8
11-Mar-10 20.3 17.8 24.5 1.9
12-Mar-10 17.2 16.4 18.2 1.3
13-Mar-10 17.1 13.7 20.3 3.8
14-Mar-10 16.9 13.2 21.0 3.8
15-Mar-10 16.0 11.4 21.0 3.5
16-Mar-10 14.0 8.6 20.3 3.1
17-Mar-10 14.0 9.1 20.4 2.8
18-Mar-10 13.6 8.2 18.6 3.5
19-Mar-10 14.3 5.8 21.8 3.1
20-Mar-10 15.2 5.8 25.1 3.8
21-Mar-10 16.8 11.5 21.3 2.2
22-Mar-10 15.4 10.7 19.6 3.5
23-Mar-10 15.3 9.1 19.5 3.8
24-Mar-10 16.1 5.7 26.0 3.8
25-Mar-10 19.8 12.3 26.1 3.8
26-Mar-10 19.5 13.9 24.3 4.1
27-Mar-10 18.7 7.5 27.9 4.4
28-Mar-10 18.9 16.7 23.2 2.2
29-Mar-10 17.3 13.8 20.8 3.5
30-Mar-10 15.9 7.4 21.2 4.1

0 Florida Automated Weather Network
* Daily averages of Penman-method Evapotranspiration.


120









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127









BIOGRAPHICAL SKETCH

Maricruz was born in San Jose, Costa Rica. She grew up surrounded by farms

and developed a strong interest for fruit production. She pursued a Bachelor of Science

in Plant Sciences at the University of Costa Rica and graduated from it in 2005, after

that she continued with advances studies in Plant Science and graduated from it in

2007. From July 2005 to May 2008 she worked as a research assistant at the

Postharvest Technology Laboratory of the University of Costa Rica as a coordinator of

the evaluations of liquid 1-MCP Technology (AgroFresh Inc. PA.) in tropical fruits. Since

August 2008 she was a master's student and worked in Dr. Bielinski Santos horticultural

program at the Gulf Coast Research and Education Center (Balm, FL), a unit in the

Institute of Food and Agricultural Sciences (IFAS) at the University of Florida.


128





PAGE 1

1 EFFECTS OF IRRIGATION VOLUMES AND FREQUENCIES ON THE GROWTH, YIELD AND POSTHARVEST QUALITY OF WINTER STRAWBERRIES GROWN ON SANDY SOILS By MARICRUZ RAMIREZ SANCHEZ A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2010

PAGE 2

2 2010 Maricruz Ramrez Snchez

PAGE 3

3 To Juan and Yolanda

PAGE 4

4 ACKNOWLEDGMENTS I thank my parents and siblings for all their love and support, as well as my godfathers and friends for being there constantly. I would like to thank my advisor Dr. Bielinski Santos for giving me this opportunity and for his words of wisdom. I also would like to thank the members of my committe e Dr. Craig Chandler and Dr. Steven Sargent, the Horticulture Laboratory staff of the Gulf Coast Research and Education Center and the Postharvest Laboratory staff of the Horticultural Sciences Department.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF FIGURES ........................................................................................................ 10 ABSTRACT ................................................................................................................... 12 CHAPTER 1 INTRODUCTION .................................................................................................... 14 2 LITERATURE REVIEW .......................................................................................... 16 Strawberry P ostharvest Quality .............................................................................. 17 Production System .................................................................................................. 20 Water Management ................................................................................................ 21 Importance of th e Study .......................................................................................... 28 3 EFFECTS OF IRRIGATION VOLUMES AND FREQUENCIES ON THE GROWTH, YIELD AND POSTHARVEST QUALITY OF STRAWBERRY FESTIVAL GR OWN ON SANDY SOILS, 2008 09 SEASON ................................. 30 Materials and Methods ............................................................................................ 30 Results and Discussion ........................................................................................... 34 200809 Strawberry Season Environmental Conditions ................................... 34 Plant Diameter and Chlorophyll Content .......................................................... 34 Root and Shoot Dry Weight .............................................................................. 35 Foliar Nutrient Concentration ............................................................................ 35 Pr e storage Strawberry Fruit Quality ................................................................ 37 Post storage Strawberry Fruit Quality .............................................................. 38 Early and Total Yields ...................................................................................... 39 4 EFFECTS OF IRRIGATION VOLUMES AND FREQUENCIES ON THE GROWTH, YIELD AND POSTHARVEST QUALITY OF STRAWBERRY FESTIVAL, FLORIDA RADIANCE AND WINTER DAWN ON S ANDY SOILS, 200910 SEASON ................................................................................................... 70 Materials and Methods ............................................................................................ 70 Results and Discussion ........................................................................................... 74 200910 Strawberry Season Environmental Conditions ................................... 74 Plant Diameter and Chlorophyll Content .......................................................... 74 Root and Shoot Dry Weight .............................................................................. 75 Foliar Nutrient Concentrations .......................................................................... 75 Pre storage Strawberry Fruit Quality ................................................................ 78

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6 Post storage Strawberry Fruit Quality .............................................................. 80 Early and Total Yield ........................................................................................ 83 5 SUMMARY AND CONCLUSIONS ........................................................................ 104 APPENDIX: TEMPERATURE DATA FROM FAWN WEATHER REPORT FOR BALM, FLORIDA DURING 2008 09 AND 2009 10 STRAWBERRY SEASONS .. 111 LIST OF REFERENCES ............................................................................................. 121 BIOGRAPHICAL SKETCH .......................................................................................... 128

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7 LIST OF TABLES Table page 3 1 Average environmental conditions from October 2008 to March 2009 from FAWN weather report for Balm, Florida. ........................................................... 44 3 2 Effects of irrigation volumes and frequencies on Strawberry Festival plant diameter and leaf chlorophyll content at 6, 12, and 18 weeks after transplant (WAT). 200809 Season. .................................................................................... 44 3 3 Effects of irrigat ion volumes and frequencies on Strawberry Festival root and shoot dry weight at 25 weeks after transplant. 200809 Season. ................ 45 3 4 Effects of irrigation volumes and frequencies on Strawberry Festival foliar nutrient concentration at 6 weeks after transplant. 200809 Season. ................. 46 3 5 Effects of irrigation volumes and frequencies on Strawberry Festival foliar nutrient concentration at 12 weeks after transplant. 200809 Season. ............... 47 3 6 Effects of irrigation volumes and frequencies on Strawberry Festival foliar nutrient concentration at 24 weeks after transplant. 200809 Season. ............... 48 3 7 Effects of irrigation volumes and frequencies on Strawberry Festival fruit quality; prestorage (8 days at 5C) evaluation at14 weeks after transplant. 2008 09 Season. ................................................................................................ 49 3 8 Effects of irrigation volumes and frequencies on Strawberry Festival fruit quality; prestorage (8 days at 5C) evaluation at 18 weeks after transplant. 200809 Season. ............................................................................................... 50 3 9 Effects of irrigation volumes and frequencies on Strawberry F estival fruit quality; prestorage (8 days at 5C) evaluation at 19 weeks after transplant. 200809 Season. ................................................................................................ 51 3 10 Effects of irrigation volumes and frequencies on Strawberry Festival fruit quality prestorage (8 days at 5C) evaluation at 22 weeks after transplant. 2 008 09 Season. ................................................................................................ 52 3 11 Effects of irrigation volumes and frequencies on Strawberry Festival fruit quality post storage (8 days at 5C) of fruit harvested at 19 weeks after transplant. 200809 Season. .............................................................................. 53 3 12 Effects of irrigation volumes and frequencies on Str awberry Festival fruit quality post storage (8 days at 5C) evaluation of fruit harvested at 22 weeks after transplant. 200809 Season. ...................................................................... 54 4 1 Average environmental conditions from October 2009 to March 2010 from FAWN weather report for Balm, Florida. ........................................................... 87

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8 4 2 Effects of irrigation volumes and frequencies on strawberry plant diameter at 6, 14, and 17 weeks after transplant (WAT). 200910 Season. .......................... 88 4 3 Effects of irrigation volumes and frequencies on strawberry leaf chlorophyll content at 6, 14 and 17 weeks after transplant (WAT). 200809 Season. .......... 89 4 4 Effects of irrigation volumes and frequencies on strawberry root dry weight at 22 weeks after transplant. 200910 Season ...................................................... 90 4 5 Effects of irrigation volumes and frequencies on strawberry shoot dry weight at 22 weeks after transplant. 200910 Season. .................................................. 91 4 6 Effects of irrigation volumes and frequencies on strawberry foliar nutrient concentration at 6 weeks after transplant. 200910 Season. .............................. 92 4 7 Effects of irrigation volumes and frequencies on strawberry foliar nutrient concentration at 14 weeks after transplant. 200910 Season. ............................ 93 4 8 Effects of irrigation volumes and frequencies on strawberry foliar nutrient concentration at 17 weeks after transplant. 200910 Season. ............................ 94 4 9 Effects of irrigation volumes and frequencies on strawberry fruit quality prestorage (8 days at 7C) evaluation at 14 weeks after transplant. 200910 Seaso n. .............................................................................................................. 95 4 10 Effects of irrigation volumes and frequencies on strawberry fruit quality prestorage (8 days at 7C) evaluation at 17 weeks after transplant. 200910 Season. .............................................................................................................. 96 4 11 Effects of irrigation volumes and frequencies on strawberry fruit quality prestorage (8 days at 7C) evaluation at 20 weeks after transplant. 200910 Season. .............................................................................................................. 97 4 12 Effects of irrigation volumes and frequencies on strawberry fruit quality post storage (8 days at 7C) evaluation at 14 weeks after transplant. 20092010 Season. .............................................................................................................. 98 4 13 Effects of irrigation volumes and frequencies on strawberry fruit quality post storage (8 days at 7C) evaluation at 17 weeks after transplant. 20092010 S eason. .............................................................................................................. 99 4 14 Effects of irrigation volumes and frequencies on strawberry chroma post storage (8 days at 7C) at 17 weeks after transplant 200910 Season. ............ 100 4 15 Effects of irrigation volumes and frequencies on strawberry fruit quality post storage (8 days at 7C) evaluation at 20 weeks after transplant. 20092010 Season. ............................................................................................................ 101

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9 4 16 Effects of irrigation volumes and frequencies on strawberry early and total yield. 200910 Season. ..................................................................................... 102 A 1 Daily average of data from FAWN weather report taken at 60 cm from soil from October 2008 to March 2009, Balm, FL. .................................................. 111 A 2 Daily average of data from FAWN weather report taken at 60 cm from soil from October 2009 to March 2010, Balm, FL. .................................................. 116

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10 LIST OF FIGURES Figure page 3 1 Effects of irrigation volumes and frequencies on Strawberry Festival A) plant diameter (cm) at 18 weeks after transplant, B) shoot dry weight 25 weeks after transplant. 200809 Season. ........................................................... 55 3 2 Effects of irrigat ion volumes and frequencies on Strawberry Festival foliar nutrient content at 6 weeks after transplant. A) nitrogen (N), B) phosphorus (P). 2008 09 Season. ......................................................................................... 56 3 3 Effects of irrigation volumes and frequencies on Strawberry Festival foliar content at 6 weeks after transplant. A) calcium (Ca), B) magnesium (Mg). 200809 Season. ................................................................................................ 57 3 4 Effects of irrigation volumes and frequencies on Strawberry Festival foliar content at 6 weeks after transplant. A) boron (B), B) iron (Fe). 200809 Season. .............................................................................................................. 58 3 5 Effects of irrigation volumes and frequencies on Strawberry Festival foliar content at 6 weeks after transplant. A) zinc (Zn), B) manganese (Mn) 200809 Season. ......................................................................................................... 59 3 6 Effects of irrigation volumes and frequencies on Strawberry Festival foliar content at 12 weeks after transplant. A) boron (B), B) zinc (Zn). 2008 09 Season. .............................................................................................................. 60 3 7 Effects of irrigation volumes and frequencies on Strawberry Festival manganese (Mn) foliar content at 12 weeks after transplant. Season 200809. ...................................................................................................................... 61 3 8 Effects of irrigation volumes and frequencies on Strawberry Festival foliar content at 24 weeks after transplant. A) phosphorus (P), B) calcium (Ca). 200809 Season. ................................................................................................ 62 3 9 Ef fects of irrigation volumes and frequencies on Strawberry Festival foliar content at 24 weeks after transplant. A) copper (Cu), B) boron (B). 200809 Season. .............................................................................................................. 63 3 10 Effects of irrigation volumes and frequencies on Strawberry Festival fruit firmness (N) pre storage (8 days at 5C) at 14 weeks after transplant. 200809 Season. ......................................................................................................... 64 3 11 Effects of irrigation volumes and frequencies on Strawberry Festival fruit lightness (L*) prestorage (8 days at 5C) at 19 weeks after transplant. 200809 Season. ......................................................................................................... 65

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11 3 12 Effects of irrigation volumes and frequencies on Strawberry Festival fr uit pre storage (8 days at 5C) analysis at 22 weeks after transplant. A) total tritatable acidity (% citric acid), B) lightness (L*). 200809 Season. .................... 66 3 13 Effects of irrigation volumes and frequencies on Strawberry Festival fruit post storage (8 days at 5C) analysis of fruit harvested at 19 weeks after transplant. A) total titratable acidity (% citric acid), B) lightness (L*). 2008 09 Season. .............................................................................................................. 67 3 14 Effects of irrigation volumes and frequencies on Strawberry Festival fruit post storage (8 days at 5C) analysis of fruit harvested at 22 weeks after tr ansplant. A) firmness (N), B) chroma (C*). 200809 Season. ........................... 68 3.15 Effects of irrigation volumes and frequencies on Strawberry Fest ival early yield (A) and total yield (B). 20082009 Season. ................................................ 69 4 1 Effects of irrigation volumes and frequencies on soil water cont ent (%). 200910 Strawberry Season. ..................................................................................... 103

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12 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science EFFECTS OF IRRIGATION VOLUMES AND FREQUENCIES ON THE GROWTH, YIELD AND POSTHARVEST QUALITY OF WINTER STRAWBERRIES GROWN ON SANDY SOILS By Maricruz Ramirez Sanchez August 2010 Chair: Bielinski M. Santos Major: Horticultural Science Florida is the second largest strawberry producing state in the U.S with a planted area of more than 3,000 ha. Strawberry production has a high water requirement for crop establishment, growth, and freeze protection. Florida strawberry growers use a wide range of irrigation programs to grow the crop. Contamination of ground water resources has profound environmental implications that make necessary the regulation and conservation of this resource The objec tive of this study was to compare plant growth, fruit yield and postharvest quality of strawberry cultivars under various drip irrigation volumes and frequencies The irrigation volumes were 1.8, 3.6 and 5.4 L/m/day and the two frequencies were one and two cycles per day and they were tested during the 200809 and 200910 strawberry seasons. Strawberry plant diameter and foliar nutrient content were determined at 6, 12 and 18 weeks after transplanting, root and shoot dry weight at the end of the season and mark etable fruit through 24 harvests per season. Fruits were collected from each plot to determine total titratable acidity and soluble solids content of each treatment at harvest All nutrients were in adequate range for all irrigation programs through both seasons.

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13 Early yield of Strawberry Festival during the first season was not affected by irrigation programs, ranging between 7.8 and 9.0 t/ha. The lowest total yield was found in plots irrigated twice per day with 1.8 L/m/day, whereas the highest fruit yields were obtained in plots irrigated with either 3.6 or 5.4 L/m/day in one or two cycles, but with better results when irrigated in two cycles per day ranging between 29.6 and 30.0 t/ha. Higher water volume resulted in higher Strawberry Festival plant diameter and shoot dry weight. T otal t itratable acidity was higher at 22 weeks after transplant for the irrigation volume of 1.8 L/m/day. In the second season there was a cultivar effect for both early and total yield. The highest early yield was obtained by Florida Radiance, and Winter Dawn had the highest total yield of 13.40 ton/ha. Winter Dawn had the highest root dry weight. There were no effects on t otal t itratable acidity and soluble solids content among irrigation programs. Winter Dawn had the highest total titratable acidity and the lowest soluble solids content i n most evaluations. The results showed that reducing irrigation volumes from 5.4 L/m/day over a period of 24 weeks to 1.8 L/m/day at a frequency of twice a day for the first eight weeks and then 3.6 L/m/day at a frequency of twice a day for the remaining 16 weeks could save an estimated of 11 million m3 of water per 24week season for the Florida strawberry industry as a whole. The suggested irrigation volumes and frequencies can be used without causing plant stress, reducing yield and compromising postharvest quality.

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14 CHAPTER 1 INTRODUCTION Florida is the second largest strawberry producing state in the U.S. (Tomlinson et al., 2004). The planted strawberry area in Florida for 2008 was 3,359 ha, with a value of production of $330 million (U.S .Department of Agriculture, 2010). Hillsborough County, located in west ce ntral Florida, has the largest planted area in the state. In Florida sandy soils, the amount of water that can be stored and available to the plants is limited. Drip irrigation is the predominant irrigation system for strawberry production, but in order to have the highest efficiency it requires proper design, installation and operation, which includes knowing the water quality and the fields size, drainage characteristics, etc. (Clark and Smajstrla, 1996). It also allows fertilizer application throughout the season and reduces foliar diseases and weeds (by wetting only the soil in the beds and not in the row middles) (Locascio, 2005). Precise, highfrequency, low volume irrigation reduces the potential for waterlogging and also helps to lower drainage requirements. Irrigation scheduling consists of knowing when and how much water to apply in a way that satisfies crop water needs with minimum leaching (Simonne and Hochmuth, 2006). Insufficient water application can result in crop stress and reduced yields. In strawberries, Kruger et al. (1999) and Kirnak et al. (2003) have shown a positive influence of proper irrigation on yield and fruit size and quality. Ostrowska and c strawberry fruits and premature ripening. It was also found that there is a significant effect of irrigation on strawberry flavor (Hoberg et al., 2002). Irrigation management has been found to be directly linked not only to yield and economic value of vegetable crops, but also to the long term sustainability and environmental impact of vegetable

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15 production (Simonne et al., 2005). In Florida, algal blooms have led to eutrophication, degraded coastal water quality, and deterioration of coral reefs. Marine algal blooms are caused by elevated nitrogen (N) and phosphorus (P) nutrient levels delivered to the water bodies through leaching and runoff (Finkl and Charlier, 2003). According to Smajstrla et al. (2002) other consequence of over irrigation is the exces sive waste of water, fertilizers and energy (required for pumping from wells ). Modern agriculture has the challenge to produce increased quantities of fruits and vegetables for a growing population, while dealing with ever higher production costs and soci etal demands to minimize the negative environmental impact of production practices. Under these circumstances, growing systems must be more efficient to be competitive and sustainable. There is a wide range of irrigation practices used by strawberry grower s in Florida, in terms of irrigation volume and frequency of application. Therefore, the objective of this study was to determine the influence of irrigation volume and frequency on plant growth, fruit yield and postharvest quality. This information can th en be used to develop improved water use recommendations for production of strawberry in west central Florida and other areas with soils and a climate similar to that of west central Florida. The null hypotheses of this research were: a) Water volume and fr equency of application have no effect on plant growth, yield, and fruit quality. b) The interaction between drip irrigation treatment and cultivar has no effect on plant growth, yield, fruit quality or postharvest shelf life

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16 CHAPTER 2 LITERATURE REVI EW Strawberry (Fragaria x ananassa ) belongs to the Rosaceae Family. It resulted from a natural hybrid between F. chiloensis native to the west coast of North and South America, and F. virginiana, native to the east coast of North America (Peres et al., 2009). It is a widely adapted crop grown in geographically diverse areas ranging from low latitude tropical and subtropical areas (e.g. Mexico, Colombia, Costa Rica, and Florida) to highlatitude continental areas (e.g. Poland, Russia, Germany, Belgium, and China) (Darnell et al., 2003). Strawberry is a herbaceous perennial plant with a central stem or crown from which leaves, roots, stolons (runners), branch crowns and inflorescences emerge (Hancock, 1999). Roots emerge from the base of crowns when they com e in contact with the soil. The roots begin branching at 2 to 5 cm and if adequate water is available, they keep branching into a fibrous mass. There are 20 to 30 primary roots, hundreds of secondary, tertiary, and higher order roots (Hancock, 1999). Accor ding to Dana (1980) mentioned by Hancock (1999) there are up to 50 to 90% of the strawberry roots concentrated in the upper 1015 cm of the soil. Strawberry is a popular fruit with high visual appeal and desirable flavor but highly perishable, being susceptible to mechanical injury, water loss, decay and physiological deterioration (Shin et al., 2008). The principal strawberry currently grown in Florida is Strawberry Festival, a cultivar with firm fruit, a sturdy bush that does not yield large quantities of fruit on any one date, and produces very few cull fruit. The external color of fully mature fruit is deep red (Chandler et al., 2000). Winter Dawn is a cultivar grown in Florida for its ability to produce high early season yields. It is usually a relatively small plant with a shallow root system (Santos

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17 and Chandler, 2009). The external color of fully mature fruit is mostly deep red and glossy, although the color immediately surrounding the achenes is an orange red. Fruit of Winter Dawn are generally less firm than those of Strawberry Festival. Florida Radiance is an offspring of Winter Dawn. It tends to have a larger canopy than Winter Dawn and a more open plant habit than Festival. Its achenes are slightly sunken, giving the fruit a smooth appearance. The external fruit color is a glossy bright to dark red (Chandler et al., 2009). Strawberry Postharvest Quality Strawberries are one of the most perishable fruit crops. They have a high metabolic rate and senesce in a relative short time, even without organisms causing decay. Respiration rate of strawberries is high, ranging between 20 and 40 mg CO2Fruit quality is a combination of appearance, including color and gloss, texture, flavor, freshnes s, freedom of injury and decay and nutritional value (Mitchel et al., 1996). Azodanlou et al. (2003) found that aroma and sweetness are two of the most important quality attributes for strawberries consumers. Del Pozo Insfran et al. (2006) described the flavor of fresh strawberries as highly dependent on both sweetness and aroma active compounds but that those sensory attributes can vary significantly from harvest to harvest. Fruit ripeness, cultivar, irrigation, and fertilization are major factors that affect taste quality of a product, in this case strawberries (Kafkas et al., 2007). /kgh at a temperature of 5C (Kader, 2002). Strawberries do not exhibit a climacteric respiratory pattern, but their ripening is associated with biochemical changes including increases in pectins, hemicelluloses and several enzymes associated with anthocyanin and fatty acid biosynthesis (Hancock, 1999). Jouquand et al. (2008) showed a high variation among strawberry genotypes grown in

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18 Florida in terms of flavor, sweetness and tar tness preferences and also that aroma volatiles and sugar levels must be balanced to ensure a flavor appealing to consumers. T otal t itratable acidity is a measurement of the total acid concentration contained within a food (Sadler and Murphy, 1998). In frui ts, acids contribute to color stability, and inhibit enzyme activity (Perkins Veazie, 1995). The levels of organic acids present often represent an important quality variable. I n strawberry fruit the main acids are citric, malic, succinic and quinic acids (Kays, 1997). Titratable acidity is generally expressed as percent of citric acid, the predominant organic acid in strawberry. It ranges from 0.45% to 1.81%, depending on fruit maturity, cultivar, nutritional and environmental impact (Perkins Veazie, 1995) Titratable acidity gradually declines during ripening (Hancock, 1999). In a study on strawberry fruit at six stages of maturity (white, pink, red red full red, and dark red) Mnager et al. (2004) found that the levels of titratable acidity were not different for the two first stages and then significantly decreased during Soluble solids content of strawberry fruit is composed of sugars, acids, and other substances dissolved in cell sap (Perkins Veazie 1995). Sugars are the main soluble components in ripe strawberry fruit, with glucose, fructose, and sucrose accounting for almost 99% of the total sugar content (Kafkas et al. 2007). According to Hancock (1999) soluble solids and titratable acidity are dependent on strawberry cultivar and environmental conditions. Kafkas et al. (2007) noted that the accumulation of organic acids, ascorbic acid, and soluble sugars was strongly dependent on genotype. Del Pozo Insfran et al. (2006) found significant differences in soluble solids and phytochemical concentrations among strawberry genotypes grown in a winter hill production system

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19 the latter stages of ripening Chandler et al. (2003) suggested that to identify strawberry genotypes that produce relatively high soluble solids in winter, fruit samples should be collected and analyzed two or more times over the season. The fruit of some cultivars tastes acidic because there are not enough sugars in the fruit to balance high acid levels. Gunness et al. (2009) found that sweetness and sourness of strawberry rated similarly for bulk puree and individual fruit samples. Color can be defined as the interpretation by the brain of a light signal coming from a sample. Color representation is a threedimensional concept various color system have been suggested (Francis, 1998). In the CIE (International Commission on Ilumination) L*, a* and b* (CIELAB) color space the lightness coefficient (L*) ranges from black (0) to white (100). For any value of L*, the coordinate (a*, b*) locates the color in a rectangular coordinate gr id perpendicular to the L* axis. Chroma (C*) is calculated as (a*2 + b*2) Firmness of fruit relates to the storability and resistance to injury of products during marketing (Dving and Mge, 2002). Fruit firmness can be determined by measuring penetration force using an Instron Universal Testing Machine (Instron Corporation, Norwood, MA ) (Kader, 2002). The handling and storage conditions to and represents the hypotenuse of a right triangle created by joining points (0, 0), (a*, b*), and (a*, 0). The hue angle (h*) is defined as the angle between the hypotenuse and 0 on the a* value (bluish green/redpurple) axis (McGuire, 1992). Shin et al. (2008) found that lightness, chroma and hue angle of strawberry harvested at the white tip stage were greater during storage than of fruit harvested red ripe, and also that the low er the temperature the higher the values of L*, C* and h of strawberry harvested with white tips.

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20 which many products are exposed after harvest may also significantly alter their textural pr operties. The loss of water due to improper control of relative humidity to which many products are exposed after harvest can result in serious textural quality losses (Kays, 1997). Strawberries soften greatly between green and white ripening stages and co ntinue to soften as color development progresses (Perkins Veazie, 1995). At harvest, Shin et al. (2008) found that the firmness of white tip strawberries (74 N) was higher than that of red ripe fruit (39 N). Mnager et al. (2004) found that firmness decreased from white to half red fruits and then appeared to remain constant level off. Dving and Mge (2002) found that firmness and soluble solids were mostly not significantly correlated and that fruit firmness decreased with increased storage temperature. P roduction System The annual hill culture method for production, also known as plasticulture, is used for strawberry production but also for other vegetables like tomato (Solanum lycopersicum ), bell pepper ( Capsicum annuum ), eggplant ( Solanum melongena), an d watermelon ( Citrullus lanatus ); approximately 34,398 ha are planted with this production system in Florida ( U.S.Department of Agriculture, 2010). It is a management tool that enables vegetable producers to obtain greater returns per unit by modifying the microclimate around the crop (Lamont, 2005). Plasticulture includes soil fumigation, a layer of polyethylene mulch over raised beds and drip irrigation. Lamont (1993) and Simonne and Hochmuth (2010) mention some of the advantages of plasticuture: earlier and higher overall yields, because the raised beds promote early season soil warming; reduced evaporation since the soil is being covered; improved weed control; reduce d fertilizer leaching, as drip irrigation systems allow for better fertilizer management ; reduced soil compaction; elimination of root pruning; production of a cleaner product

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21 since the product is not in contact with soil; reduced risk of flooding injury because raised beds provide for better drainage; and finally, ability to double or triple crop. The main disadvantages are the need for specialized equipment to make the raised beds and lay the drip tape and plastic mulch; the cost of the plastic mulch and drip tape; and the expense of removing and disposing of the plastic mulch and drip tape at the end of the season. Strawberries are picked with caps (calyxes) attached. Fruit must be loosely held in the hand without squeezing. Any squeezing of the fruit will cause bruising injury and discoloration. Strawberries must be handled gently to ensure quality (Mitchell, 1996). Mitcham and Mitchell (2002) mentioned that factors that can impact fruit quality, e.g. preharvest disease control, field sanitation, harvest maturity fruit i njuries at harvest and packing fruit disease and defects, exposure t o light and heat and rate of cooling. Kader (2002) also mentions that appropriate temperature management, including rapid cooling and maintenance of low pulp temperatures, is the most important factor to maximize postharvest life (Kader, 2002). Nunes et al. (1995) found that when cooling of strawberry fruit was delayed for 6 h at 30C, the berries were significantly softer, more shriveled, had less attractive color, and the acidity, soluble solids content, sugar and ascorbic acid levels were lower than in fruit that were quickly cooled. Water Management Florida has a humid subtropical climate and average annual rainfall for most of the state is between 1270 and 1524 mm. However, the typically erratic distribution of rain and Floridas predominantly sandy so ils make frequent irrigation necessary in order to avoid plant stress during drought conditions (Haman and Izuno, 2003). The aim of irrigation management is to control plant water status for the purpose of maximizing

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22 crop production while conserving water. Plant water status is determined by the atmospheric and soil environment, and by water transport characteristics of the plant (Hsiao, 1990). There is a difference between crop water requirements and irrigation or production system water requirements. Crop water requirements refer to the water needs for evapotranspiration (ET) and plant growth, and depend on crop development and climatic factors. Irrigation requirements are determined by crop water requirements, but also by the characteristics of the irrigation system, management practices and the soil characteristics (Simonne and Dukes, 2009). In strawberry, more water is applied than what plants actually use because losses due to leaching, evaporation, inefficient application, and an inadequate ability to assess water requirements on a daily basis (El Farhan and Pritts, 1997). Water transpired by plants and evaporation from the soil surface are generally combined and defined as evapotranspiration (ET) which is the total water loss through plants and soil s urface (Kirda et al, 1999). Evaporation and transpiration occur simultaneously and there is no easy way of distinguishing between the two processes. Apart from water availability in the topsoil, evaporation from a cropped soil is mainly determined by the f raction of solar radiation reaching the soil surface (Allen et al., 1998). Transpiration increases during canopy development as a result of increasing surface area. The enlarged canopy intercepts more radiation and therefore absorbs more energy for transpi ration (Hsiao, 1990). The rate of evaporation expresses the amount of water lost from a cropped surface in units of water depth. While evaporation is easily measured, transpiration is not. Values of ET for a crop are usually expressed as the amount of water lost (inches, cm, mm) per unit of time (hour, day, week, month,

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23 season, or year) (Whitty et al., 2002) In horticultural crops, changes in water status alter the general condition of the product with economic losses being due to both decreased quali ty and product weight (Kays, 1999). In zucchini, Bhella and Kwolek (1984) found that drip irrigation and plastic mulch increased plant growth and yield, and reduced the number of days to bloom after planting and the percentage of culls. In strawberries, Kr ger et al. (1999) and Kirnak et al. (2003) have shown a positive influence of proper irrigation on yield and fruit size and quality in comparison to nonirrigated plants. Kirnak et al. (2001) also found that water stress in strawberry plants reduced dry m atter and c hlorophyll content. In addition, Kirschbaum et al. (2004) found that the greater yields for plants grown at field capacity was a function of increased fruit number and weight, while the number of fruit per plant was affected by the amount of water applied, rather than by irrigation frequency. weight, and frui t ripening. Also, Hoberg et al. (2002) detected a significant effect of irrigation on the flavor of str awberries. In west central Florida, the historical Penman reference method (ETo) ranges from 0 to 5.08 mm/day (0.08 to 0.20 inches/day) (Simonne and Dukes, 2009) The weather variables affecting evapotranspiration are radiation, air temperature, humidity, and wind speed. Water deficit causes fruit yield reductions by decreasing flower number, fruit set, numbers of fruit per plant, and fruit size. The effects on vegetative growth are more pronounced than on yield (El Farhan and Pritts, 1997). Chandler and Ferree (1990) evaluated the response of two strawberry cultivars to drought stress and found that it reduced photosynthesis and transpiration, although the effect was more pronounced in

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24 one cultivar than the other. Sav et al. (1993) noted that strawberry plants can tolerate drought by allowing the leaves to reach negative osmotic potentials, with accumulation of solutes in less elastic tissues. This adaptation facilitates continued water uptake from drying soil. Liu et al. (2007) evaluated the effects of partial root zone drying, which consisted in using irrigation to alternately wet and dry two spatially distinct parts of the plant root system. They concluded that given the same amount of water, partial root zone drying had no advantage compared to deficit irrig ation in maintaining plant water status. Both treatments reduced yield. In addition to their direct effect on plant growth, water deficits can affect crop management practices. For example the efficacy of many herbicides and other pesticides depends on soi l moisture; plants under drought stress may not respond to foliar applied chemicals, or may be damaged by chemical burns. Finally, nutrient utilization and fertilization practices are influenced by the moisture status of the crop plants (Whitty et al., 2002) Simonne et al. (2003) described irrigation scheduling as knowing when to start irrigation and how much to apply, in a way that satisfies crop water needs, conserves water, and does not leach mobile nutrients. Frequent, low volume applications allow the soil moisture content in the root zone to be maintained and are always better than infrequent and long irrigation cycles (Haman and Smajstrla, 2005). According to Phene and Beale (1976) daily low rate application of nitrogen and potassium with a highfreq uency trickle irrigation system improved nutrient uptake efficiency and reduced leaching loss of nutrients in humid regions. In cucumber, Ells et al. (1989) reported that the best combination of high yield, high water use efficiency, and fewest number of i rrigation was obtained if cucumbers were irrigated when the scheduling program

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25 determined that 40% of the available water was depleted, applying only 70% of the water that the program indicated was required. In strawberries, Dwyer et al. (1987) found that total production is increased by irrigation applied at times of moderate water stress and that a few applications, applied at the time required by the plants is as beneficial as numerous applications scheduled routinely. Using tensiometers to schedule irr igation on strawberries, Serrano et al. (1992) found that irrigation scheduling at 0.01 MPa was the most productive treatment. Kirschbaum et al. (2004) suggested that the use of both hydrologic balance equation and tensiometer would be adequate for planni ng irrigation schedules. According to their results, the strawberries water requirement in the conditions of their study was around 800 mm/year and the fruit size was affected by water rates. Krger et al. (1999) showed that the irrigation of strawberries using the climatic water balance model could be a decisionmaking tool because it is less labor intensive and time consuming than tensiometer measurements. The soil was saturated each year to field capacity (100% available water, AW) and then the soil mois ture should range between 80% and 60% AW for optimal plant growth. According to this model, irrigation should start when AW falls below 60% in the layer between 0 and 20 cm below the surface by subtracting the daily water balance (DW) from 100% AW on a dai ly basis. The daily water balance DW=ET P where ET is the evapotranspiration and P is rainfall measured in the field. Hoppula and Salo (2007) suggested that tensiometers are a suitable tool for strawberry irrigation scheduling because plants water consumption varies considerably depending on the growth stage, fruit load, and environmental factors. Finally, Gutal et al. (2005) found that by applying water to the strawberry crop every other day with an amount

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26 equal to 85% of the twoday pan evaporation gave the highest water use efficiency and fruit yield. The vegetable production in the west central Florida is primarily on flatwoods sites, consisting of extremely flat Spodosols with the spodic horizon typically beginning at a depth of 1 to 1.5 m (McNeal et al., 1995). Sandy soils consist mainly of large mineral particles with very small percentages of clay, silt and organic matter and a significant number of the pores in sandy soils are large enough to drain within the first 24 h due to gravity and this porti on of water is lost from the system before plants can use it (Haman and Izuno, 2003). The available water for sand and fine sands is between a range of 33.3 to 83.33 mm/m (Haman and Izuno, 2003). Clark et al. (1993) noted that the sandy soil (sandy, silice ous, hypothermic Alfic Haplaquod) evaluated in their study appeared to have a practical horizontal wetting (capillarity) capacity of 125 to 200 mm (5 to 8 in) with a drip irrigation rate of 1.5 to 1.9 L/h (0.4 to 0.5 gal/h). The soil can affect the quality of the produce; for example sandy soils in windy locations can result in abrasions to the surface of the product (Kays, 1999). According to Simonne et al. (2003) an application uniformity of 85% to 95% is expected from a new, well designed drip irrigation system. Because trickle systems can be operated frequently they are ideally suited to soils with a low water holding capacity (Clothier et al., 1985). Water moves across the soil surface away from the drip emitter until the infiltration rate of the ponded area matches the emitter discharge rate; beyond this, free water moves into the soil by unsaturated flow (Clothier et al., 1985). A maintenance plan will reduce the effects of the agents that reduce application uniformity: small solids in suspension, organic matter, microorganisms, and chemical

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27 residues (Simonne et al., 2003). Fertilizer application efficiencies increase when fertilizer materials can be injected into the drip irrigation system (fertigation). Soluble nutrients such as nitrogen and potassium are most often applied by drip irrigation by injecting small amounts of nutrients through the season according to seasonal crop nutrient requirements (Hochmuth, 2003). Hardeman et al. (1999) found that for yield the trickle system was superior to sprinkl er for pepper and tomato and equivalent for snap bean; but fruit quality was similar for both systems. In their experiment the trickle irrigation system applied 30% less water than the sprinkler system. This would result in a significant cost savings if the grower is paying for water. In strawberries, Rolbiecki et al. (2004) evaluated drip irrigation and microsprinkler irrigation in a loose sandy soil; they found that drip irrigation was superior in water use efficiency, but there were no differences among the irrigation systems in terms of fruit size and number. Sprinkler irrigation is used to establish bare root strawberry transplants and for freeze protection. For establishment, plants are irrigated for approximately 8 h daily with overhead irrigation for 10 to 14 days. Irrigation is provided to reduce the water stress caused by the damaged root system of the transplant, the high surface temperature of the black mulch, the high ambient air temperature, and dry weather condition at the time of transplanting (Golden et al., 2003). In terms of freeze protection, the irrigation water provides heat to the plant as the temperature of the water drops to 0C and especially as it freezes. If the temperature of the flowers or fruit stays above 1.1C there will be no damage (Albregts and Howard, 1984). Because sandy soils have a low water holding capacity water moves rapidly

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28 through these soils. Therefore there is a great potential for nitrate movement to groundwater in these (Guimer et al., 1995). Simonne et al. ( 2006) described that using drip tapes with a 20 to 30cm emitter spacing and less than 900 L/100 m of irrigation volume may reduce the risk of NO3In Florida, marine algal blooms caused by elevated nitrogen and phosphorus nutrient levels delivered to water bodies through leaching and runoff have resulted in eutrophication, degraded coastal water quality, and deterioration of coral reefs (Finkl a nd Charlier, 2003). One of the main sources of nitrates in groundwater is agricultural fertilizers; reducing nutrient leaching through appropriate fertilization programs is a desired practice for strawberry production and to support the current best manage ment practices in the state of Florida (Santos and Chandler, 2009). Guimer et al. (1995) showed that a sustainable improvement of agricultural techniques can be achieved while maintaining good standards for groundwater protection in strawberry crop produc tion. leaching on a sandy soil and provide optimum irrigation management. According to Elrashidi et al. (2004) appr opriate nutrient management planning should be considered for cultivated fields to reduce nitrogen loss from soils by leaching and scheduling irrigation according to depletion of available soil water can help to reduce deep percolation (Guimer et al., 199 5). Importance of the Study The Southwest Florida Water Management District (2010) reported that public water supply and agriculture represented 80% of the water use in the district. With a growing population, water demand will increase every year. Conta mination of ground water resources has profound environmental implications that make necessary the regulation and conservation of this resource. More efficient water use is one of the main

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29 strategies for water conservation. With a planted area of 3,359 ha in 2008 (U.S. Department of Agriculture, 201 0), strawberry production has a high water requirement for crop establishment, growth, and freeze protection. Strawberry growers in Florida use a wide range of irrigation programs to grow the crop. Generating inf ormation for efficient water use will help strawberry growers to maximize crop production and water savings. For instance, if strawberry growers irrigate 1.5 h/day this represents a water volume of 5.4 L/m/day or 313,087 L/ha/week, which can be extrapolated to a total volume of 25.4 million m3 of water used by the west central Florida industry per year. However, if strawberry growers irrigate only 1 h/day a volume of 3.6 L/m/day would be used, which is equivalent to the average ETo for the strawberry season, and therefore an industry wide water savings of around 8.4 million m3 could be obtained

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30 CHAPTER 3 EFFECTS OF IRRIGATION VOLUMES AND FREQUE NCIES ON THE GROWTH, YIELD AND POSTHARVES T QUALITY OF STRAWB ERRY FESTIVAL GROWN ON SANDY SOILS, 200809 SEASON Materials and Methods This study was conducted from October 2008 to March 2009 at the Gulf Coast Research and Education Center of the University of Florida, Balm, Florida. The soil at the experimental site is a sandy, siliceous, hyperthermic Oxyaquic Alorthod with 2.1% organic matter and pH of 6.6. Planting beds were preformed with a standard bedder, 71 cm wide at the base, 61 cm wide on the top, and 25 cm high and spaced 120 cm between centers. In early September 2008, the soil was fumigated with 350 kg/ha of methyl bromide + chloropicrin (67/33, v/v). After fumigation a singledrip tape line (0.056 L/m/min, T Tape Systems International, San Diego, CA) was buried 5 cm in all plots, regardless of irrigation program, finally the beds were covered wit h black highdensity polyethylene mulch (0.04 mm thick). No preplant fertilizer was used. The experimental area was equipped with 15 L/min sprinklers for frost protection and crop establishment. Plant nutrients were supplied to the crop through the drip l ines three times per week starting on December 8 with a hydraulic injector (Dosatron, Clearwater, FL) following statewide recommendations (Peres et al., 2009), which represented approximately 10.8 L/m/week applied to all the experimental plots. Current IFA S recommendations for insect and disease control were followed (Peres et al., 2009). The treatments evaluated were combinations of three water volumes and two irrigation frequencies. The water volumes were 1.8, 3.6 and 5.4 L/m/day, while the irrigation fre quencies were one and two cycles per day. The experimental design was a randomized complete block design with four replications. On15 October 2008 bareroot

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31 strawberry transplants from nurseries in Canada were transplanted in double rows 38 cm apart, 20 pl ants per 7.6 m plot with a 1.5 m long nontreated buffer zone at the end of each plot. The cultivar evaluated was Strawberry Festival. After transplanting, overhead irrigation was used for 8 hours for the first 10 days to ensure plant establishment (the amount of water used was approximately 480,000 L/ha/day). The irrigation volumes were transformed into irrigation times and controlled with electronic timers (Nelson SoloRain, Walla Walla, WA). Treatments receiving a single irrigation per day were watered between 8 and 9 am each morning, whereas plots receiving two cycles per day were watered between 12 pm and 1 pm in addition to the morning irrigation. Strawberry plant diameter and chlorophyll content readings were taken at 6, 12, and 18 weeks after trans planting (WAT). Plant diameter was determined using five plants per plot randomly selected and measuring the widest part of the plant. Ten recently mature leaves per plot were randomly selected to measure the chlorophyll (Chl) content with a SPAD 502 (Minolta, Ramsey, NJ), an instrument developed to measure the chlorophyll content of leaves as an indirect estimate of the nitrogen status of plants (Martnez and Guiamet, 2004). A numerical SPAD (Soil Plant Analysis Development) unit, ranging from 0 to 80 is c alculated by the chlorophyll meter and used to estimate the Chl content. Foliar nutrient concentrations were determined at 6, 12 and 24 WAT. A sample of ten recently matured leaves was randomly collected from each experimental plot. Samples were dried at 7 0C in a forcedair dryer for 48 h. Once dried, leaf samples were ground using a tissue mill (Thomas Scientific Wiley mill, Swedesboro, NJ) and they were sent for analysis to a commercial lab. Root and shoot dry weight (DW) was

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32 determined at the end of the season. Five plants of each experimental plot were removed from the field and dried at 70C in a forcedair dryer for one week. The dry tissue was weighed in a precision balance (Ohaus Adventurer, Ohaus Corporation, Pine Brook Marketable fruit with the attached calyx was harvested twice a week and the weight was recorded for 24 harvests during the season starting on December 17, 2008. Marketable strawberry fruit was defined as fruit over 10 g in weight and physiologically mature with more than 80% of red skin, free of mechanical defects and insect or disease injury. Early yield was considered as the fruit weight recorded from the first 10 harvests. Initial fruit quality (prestorage) was evaluated at harvest dates of January 19 (14 WAT), February 16 ( 18 WAT), February 27 (19 WAT), and March 16 (22 WAT) 2008. Between four and ten fruit from each plot were placed in two 473 mL clamshells (Highland Corporation, Inc., Mulberry, FL) and transported to the Postharvest Horticulture Laboratory, Horticultural Sciences Department in Gainesville, Florida. One clamshell per plot was s tored overnight in a cooler at 1C to be evaluated the next day. The fruit stored at 1C were allowed to warm t o room temperature (approximately 22C) the next day. At that time three fruit per treatment were used to measure external color at equator on opposite sides of the fruit with a Minolta CR 400 chroma meter (Minolta, Ramsey, NJ). Color was expressed as lightness (L*), hue angle (h*) and chroma (C*) value. The calyxes were removed and a transvers e section of 10 mm of the fruit was cut to measure the internal fi rmness (3 mm deformation) on o pposite sides of the transverse section with an Instron 4411 (Instron Corporation, Norwood, M A ), equipped with a 3mm diameter tip and a 5kg load cell with a crosshead speed of 0.83 mm/s. NJ).

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33 This test measured individual internal fruit firmness based in the resistance of the tissue to deformation by the probe. Six fruit per treatment were frozen to be processed for later evaluations. Frozen sam ples were later thawed at room temperature, blended in a Hamilton Beach Model 908 blender (Proctor Silex, Inc, Washington, NC), and centrifuged at 15,000 rpm for 20 min on a Beckman Model J2 21 centrifuge (Beckman Coulter, Inc., Fullerton, CA). The juice o btained was filtered and then frozen in 20 mL plastic vials for later evaluations. Frozen juice vials were thawed at room temperature (approximately 22C). Five drops of the filtered supernatant were used for the measurements of soluble solids content (Brix) using a digital refractometer (Reichert AR 200, Depew, NY) One clamshell of fruit per plot harvested 19 and 22 WAT was stored in a cooler at 5 C for eight days. This temperature is notably higher than the recommendation of 0C, but was selected to represent typical commercial handling conditions and with the purpose to accelerate postharvest decay and determine shelf life. These fruit we re evaluated after eight days at 5 C for postharvest quality (post storage), and warm ed to room temperature (approximately 22C).The variables evaluated were external color (L*, C* and h*), firmness, soluble solids content (Brix) and total titratable aci dity following the same procedures described above for initial quality evaluations Total titratable acidity (TA) was measured diluting 6 mL of sample in 50 mL of distilled water. It was stirred (Metrohm 728 stirrer, Metrohm USA, Inc, Westbury, NY) and titrated (Titrino 719 S Metrohm USA Inc, Westbury, NY). Total titratable acidity was calculated with the miliequivalent factor for citric acid (0.064 g per mEq), the major organic acid in strawberries.

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34 Collected parametric data were analyzed using Statistix 9 software (Analytical Software, Tallahassee, FL). Main effects were examined for significance (P<0.05) with a regre ssion analysis to determine linear effects within each irrigation frequency. Irrigation volumes were separated using standard errors of the treatment means. Results and Discussion 200809 Strawberry Season Environmental C onditions The average environmental conditions from October 2008 to March 2009 from the Florida Automated Weather Network (2010) are shown in Table 31. The average of rain per month was 31.4 mm and three freeze events occurred on January 21 to 23, February 5 to 6 and February 21, 2008, w ith minimum temperatures of 3.3C, 4.7C, 2.1C, 2.7C, 1.4C and 0.2C, respectively (daily averages in Appendix A). Plant Diameter and Chlorophyll C ontent There were no significant differences in plant diameter between any of the irrigation volumes 6 WAT, ranging from 23.5 to 27 cm for one cycle/day and from 22.6 to 25.1 cm for two cycles, and 12 WAT, where the range was between 34.9 and 36.8 cm for one cycle/day and between 35.3 and 36.7 cm for two cycles/day., and there were no significant differences for the irrigation volumes using the frequency of one cycle per day at 18 WAT, ranging from 36.9 to 37.5 cm (Table 32). There were significant differences among 1.8, 3.6 and 5.4 L/m/day applied in two cycles per day at 18 WAT (Figure 3 1), plant diameter ranged from 35.9 to 39.4 cm increasing as the irrigation volume increased. Plant diameter of plots irrigated with 1.8, 3.6 and 5.4 L/m/day in one cycle/day ranged between 23.7 and 27 cm at 6 WAT, between 34.9 and 36.8 cm at 12 WAT and between 36.9 and 37.5 cm at 18 WAT. Plant diameter of plots irrigated with 1.8, 3.6 and 5.4 L/m/day applied in two cycles/day ranged between 22.6 and 25.1 cm

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35 and between 35.3 and 36.7 cm at 6 and 12 WAT, respectively. There was no significant effect of the irrigati on programs on chlorophyll content at 6, 12, and 18 WAT (Table 32). For Strawberry Festival, the Chl content of the irrigation programs of 1.8, 3.6 and 5.4 L/m/day applied one cycle /day ranged between 37.4 and 40.3 SPAD value at 6 WAT, between 42.9 and 44.3 SPAD value at 12 WAT and 44.7 and 45.9 SPAD value at 18 WAT. While applying 1.8, 3.6 and 5.4 L/m/day in two cycles per day the Chl content at 6 WAT ranged between 37.6 and 39.3 SPAD value, at 12 WAT between 43.5 and 44.1 SPAD value and at 18 WAT betw een 45.1 and 47.3 SPAD value. Root and Shoot Dry W eight There were no significant differences among the irrigation programs for root dry weight, ranging from 3.46 to 5.5 grams (Table 33); however, there were for shoot dry weight. Shoot dry weight of plant s irrigated in one cycle/day decreased for 1.8 to 3.6 L/m/day but increased with 5.4 L/m/day, ranging from 33.36 to 41.27 g (Figure 31). Whereas shoot DW of plants irrigated in two cycles per day increased as the irrigation volume increased, ranging between 22.82 and 29.30 g. Foliar Nutrient C oncentration Six weeks after transplant, there were significant differences among the irrigation programs on nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), iron (Fe), boron (B), manganese (Mn), and zinc (Zn) but not for potassium (K), sulfur (S) and copper (Cu) (Table 34). All the nutrients were in the adequate range according to Peres et al. (2009). The N foliar content of the irrigated plots in two cycles per day ranged between 3.30% and 3.18%, decreas ing as the irrigation volume increased (Figure 32). While the P content increased with the increase in irrigation volume when the plots were irrigated in one cycle/day, ranging from 0.27% to 0.36%, it decreased in the plots

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36 irrigated in two cycles/day ranging between 0.42% and 0.32% (Figure 32). Ca, Mg, B, and Fe content for the plots irrigated in one cycle/day was higher when the irrigation volume was 1.8 L/m/day and decreased with volumes of 3.6 and 5.4 L/m/day ranging between 1.33% and 0.59%, 0.66% and 0.38%, 40.15 and 30.01 mg/L, 66.25 and 56.92 mg/L respectively (Figures 33 and 34) but it was the opposite for the content of Zn in plots irrigated in one cycle per day, it ranged from 25.11 to 34.63 mg/L (Figure 35). Figure 35 also shows that the Mn content decreased for 3.6 and 5.4 L/m/day when they were applied in one cycle/day, ranging from 47.20 to 36.97 mg/L, but there was an increased when the irrigation volumes applied in two cycles per day increased, ranging from 36.94 to 42.68 mg/L. Twelve weeks after transplant there were significant differences among the irrigation programs on B, Zn, and Mn foliar content, but not on N, K, Ca, Mg, S, Fe, Cu, and B (Table 35). All the nutrients were in the adequate range according to Peres et al. (2009). B foliar content decreased when the plots were irrigated with high volumes in both frequencies, ranging between 51.72 and 37.19 mg/L in one cycle/day and 51.91 to 33.91 mg/L in two cycles per day (Figure 36). When the irrigation volume was applied in two c ycles per day the Zn and Mn foliar content diminished when the irrigation volume increased, ranging from 37.45 to 27.10 mg/L and from 55.33 to 35.57 mg/L, respectively (Figures 36 and 37). At the end of the season (24 WAT), there were significant differences among the irrigation programs for P, Ca, Cu, and B; but there were not for N, K, Mg, S, Zn, Mn, and Fe (Table 36). All the nutrients were in the adequate range according to Peres et al. (2009). The P content increased when the plots were irrigated wi th the higher irrigation

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37 volumes (Figure 38) for both irrigation frequencies (one and two cycles/day) ranging from 0.26% to 0.30% and from 0.24% to 0.29% for one and two cycles/day respectively. The foliar content of Ca and Cu of the plots irrigated in tw o cycles/day was lower for 1.8 L/m/day than for 3.6 and 5.4 L/m/day (Figures 3 8 and 39) ranging between 1.52% and 1.68% (Ca) and between 8.75 and 10.75 mg/L (Cu) and finally the B content of the plots irrigated in one cycle per day decreased as the irrig ation volume increased, ranging from 107.75 to 59.50 mg/L (Figure 39). Pre storage Strawberry Fruit Q uality There were no significant effects of the irrigation programs on the fruit quality parameters total titratable acidity (TA), soluble solids content, and on external color (C*, h* and L*) (Table 37) at the initial (pre storage ) evaluation 14 WAT. There was a significant effect of the irrigation programs on fruit firmness when the plots were irrigated in one cycle/day (Figure 310) but not for the plots irrigated in two cycles per day. The strawberry firmness increased as the irrigation volume increased for the plots irrigated in one cycle/day, ranging from 0.60 to 0.78 N. TA, soluble solids content, external color (L*, C* and h*), and firmness had no significant differences among the irrigation program s (Table 38) at the prestorage evaluation 18 WAT. There were not significant differences among the irrigation programs on TA, soluble solids content, C*, h*, and firmness (Table 39); but there was on L* for the frequency of two cycles per day at the prestorage evaluation 19 WAT; fruit from the plots irrigated with 1.8, 3.6 and 5.4 L/m/day had L* values that ranged between 31.44 and 32.96, being 5.4 L/m/day the one with the highest L* value (Figure 311). At the prestorage evaluation 22 WAT, for soluble solids content, C*, h*, and firmness there were no significant differences among the irrigation programs (Table 310), but there were for TA and L* for the

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38 irrigation frequency of one cycle per day. B oth TA and L* (Figure 312) of the fruit from plots irrigated in one cycle/day had the highest value for 1.8 L/m/day and diminished with higher volumes. TA ranged from 0.66% to 0.83% and L* ranged from 30.74to 32.03. Post storage Strawberry Fruit Q uality At the post storage evaluation 19 WAT there were significant differences on TA from harvested fruit from plots irrigated in one cycle/day and on L* of fruit from plots irrigated in t wo cycles/day. For soluble solids content, C*, h*, firmness, TA (two cyc les/day) and L* (one cycle/day) however, there were no significant differences (Table 311). After storage, TA of fruit from plots irrigated with 1.8 L/m/day in one cycle/day was higher than the values from plots irrigated with 3.6 and 5.4 L/m/day, where the TA was almost equal, it ranged from 0.76% to 0.84%, while L* (two cycles/day) was lower on fruit from irrigated plants with 1.8 L/m/day and increased with higher volumes ranging from 32.16 to 34.8 (Figure 3 13). At the post storage evaluation 22 WAT, f ruit harvested at the end of the strawberry season had significant differences in firmness and C* when the irrigation volume was applied in two cycles/day. There were not significant differences on TA, soluble solids content, L*, h*, C* and firmness for t he frequency of one cycle/day (Table 312). Fruit firmness after one week of storage of plots irrigated in two cycles/day was higher when the volume was 1.8 L/m/day and lower for volumes of 3.6 and 5.4L/m/day, ranging from 33.36 to 41.27 g and the opposite was for C*, where the lowest volume had the lowest C* and it increased as the volume increased, ranging from 31.78 to 33.62 (Figure 314).

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39 Early and Total Y ields Early yields were not influenced by any of the irrigation programs. For Strawberry Festival irrigation programs did not affect early yields, which ranged between 7.8 and 9.0 t/ha. There was not a significant effect on total yields when irrigation volumes were applied once per day, with an average of 27.3 t/ha. However, when the irrigation volu mes were applied twice per day, there was a significant effect on total yields. The lowest total yield was found in plots irrigated twice per day with 1.8 L/m/day, whereas the highest fruit yields were obtained in plots irrigated with 3.6 or 5.4 L/m/day, r anging between 29.6 and 30.0 t/ha (Figure 315). The results indicate that at the beginning of the season, when plants do not have a large root system and the evapotranspiration rate was lower, nutrient absorption was different depending on the irrigation program applied. Irrigation frequency had a strong effect on of macro and micro nutrients absorption. In the case of B, Ca, Mg, Mn, and Fe applying 1.8 L/m/day in one cycle per day made the strawberry plants absorb a higher content of those nutrients; but a lower foliar content of Zn and P. Applying the irrigation programs in two cycles per day only had effect on the absorption of N, P and Mn. However, differences in foliar nutrient concentration at the beginning of the season did not mean higher plant diam eter and higher early yields. The plant tissue analysis showed that the nutrients were in adequate range, even for the lowest volume (1.8 L/m/day). This volume could be used by growers in both frequencies at the beginning of the season without affecting pl ant growth. In the middle of the season (12 WAT) the irrigation programs only had an effect on Mn, Zn and B for the frequency of two cycles per day, plants from plots irrigated with the lowest volume had the highest content of those nutrients and the same happened for B content of plants irrigated in one

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40 cycle/day. Differences on some foliar nutrients did not mean bigger plants because there was no effect on plant diameter and chlorophyll content. At the end of the season, with a volume of 1.8 L/m/day appli ed in two cycles per day, Cu, P and Ca content was low, while for the irrigation frequency of one cycle per day, B content was higher with 1.8 L/m/day than with 3.6 and 5.4L/m/day. This result is similar to what Kirnak et al. (2003) found with a reduced ir rigation volume at the end of the strawberry season, P and Ca foliar concentration in mature leaves was low and that might have affected the total yields of the plants irrigated with the lowest volume, particularly with the frequency of two cycles per day. Plant growth was influenced at 18 WAT, plants from plots irrigated in two cycles per day had higher plant diameter with the highest water volume. Shoot dry weight at the end of the season had a similar pattern when the highest volume resulted in the highest shoot dry weight for both irrigation frequencies and particularly when the water volume was applied in one cycle per day. Both plant diameter and shoot dry weight had the lowest values when 1.8 L/m/day was applied in two cycles per day. Such response was most likely because of the high evapotraspiration, air and soil temperature in west central Florida at the end of the strawberry season. The effect of irrigation on shoot dry weight of strawberry plants was also found by Kirnak et al. (2003) with hi gher shoot dry weight in plants irrigated with the highest volume. Strawberries could be irrigated with 1.8 L/m/day during the first 8 WAT without significantly reducing early yields. Irrigation should occur only once per day when lower water volumes are utilized. In contrast, total yields were influenced by irrigation programs. Total yield increased in plots irrigated with 3.6 and 5.4 L/m/day per season applied in two cycles; but increasing irrigation volumes

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41 to 5.4 L/m/day did not increase strawberry yiel ds even though the plant diameter and shoot dry weight of the plants irrigated with 5.4 L/m/day the highest at the end of the season. These results appear similar to those reported by Dwyer et al. (1987), Kirnak et al. (2003), and Blatt (1984) who found an effect of irrigation scheduling on strawberry yield. The lowest total yield was obtained in plots irrigated with 1.8 L/m/day in two cycles per day and this can be related with the low plant diameter and low shoot DW obtained from the same irrigation volum e. As mentioned by Simonne and Duke (200 9 ) the crop water requirements includes the water needs for evapotranspiration and plant growth. It is possible that the lowest water volume only covered the evapotranspiration needs but not the plant growth which di rectly affects the plant yield, in addition with the water wasted because the efficiency of the drip irrigation is around 85% to 95%. According to Simonne et al. (2006) frequent and short irrigations may waste water and reduced irrigation uniformity due to a large proportion of the irrigation cycle used for system charge and flush. Serrano et al. (1992) also found yield reductions associated with the reduction on total assimilation rate because the assimilatory surface area decreased in plants irrigated at low soil water potentials. In terms of postharvest quality, water volume influenced fruit firmness at 14 WAT, fruit harvested from plots irrigated with 1.8 L/m/day in one cycle/day were softer than fruit from plots irrigated with higher water volumes. Acc ording to Morris and Sistrunk (1991) mentioned by Prange and DeEll (1997) strawberry fruit is softest after rain. It only rained the harvesting day at 14 WAT and the effect was stronger on fruit from plots irrigated with 1.8 L/m/day. There was an effect of water volume applied in one cycle/day on TA, the percentage of TA on strawberry fruit harvested at 19 WAT was high when

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42 1.8 L/m/day was applied. The same response was obtained in the prestorage evaluation at 22 WAT for the same irrigation volume and freq uency; meaning that reducing the irrigation volume at the end of the season might increase the TA. This irrigation program had also the highest L* among the treatments. Irrigating with two cycles per day had an effect on fruit firmness after storage. It was higher in fruit from plots irrigated with 1.8 L/m/day. Chroma had a smaller value for 1.8 L/m/day in two cycles per day than for the other two irrigation volumes, which means that the intensity of color of the strawberry fruit was high when the water was applied in two cycles per day. In general for strawberry grown in sandy soils, increasing the water volume to more than 3.6 L/m/day (average evapotranspirat ion of the strawberry season) did n ot increase Strawberry Festival early and total yields, but it might increase leaching and waste of water and fertilizers. On the other hand, irrigating with a volume of 1.8 L/m/day, and most likely lower volumes through the season, would result in reduction in plant growth and yield. F urther research should show i f the same effects on yields are found to confirm these results. Scheduling strawberry irrigation based on weather conditions to satisfy the strawber ry water needs can be less labor intensive and time consuming as mention ed by Krger et al. (1999). A straw berry grower could irrigate with a water volume of 3.6 L/m/day in one or two cycles per day, although the frequency of two cycles per day can result in higher yields. The irrigation volume of 1.8 L/m/day in one or two cycles per day could be use d at the beginning of the season when plant size is still small. Then the volume coul d be increased to 3.6 L/m/day when the size of the plants

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43 gets bigger and the water needs increase to satisfy crop water requirements and at the same time using the resourc es efficiently.

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44 Table 31. Average environmental conditions from October 2008 to March 2009 from FAWNMonth weather report for Balm, Florida. Air Temperature (C) Soil Temperature (C) Rain (mm) Relative humidity (%) Solar irradiation (w/m2 ) Avg Min Max Avg Min Max October 22.3 1.6 33.1 24.6 19.5 26.8 35.6 73.0 185.2 November 16.6 0.6 31.9 20.1 16.6 23.1 37.8 71.0 154.0 December 17.3 1.2 29.1 18.2 15.6 20.3 34.5 75.0 136.6 January 14.5 4.6 29.0 16.7 12.0 19.8 37.1 71.0 148.8 February 15.1 2.6 29.5 16.6 12.0 19.5 12.7 66.0 186.6 March 19.0 1.0 31.4 19.3 14.9 21.8 30.5 69.0 215.4 Florida Automated Weather Network Table 32. Effects of irrigation volumes and frequencies on Strawberry Festival plantdiameter and leaf chlorophyll content at 6, 12, and 18 weeks after transplant(WAT). 2008 09 Season. Volume Frequency Plant diameter (cm) Chlorophyll content (SPAD value) (L/m/day) (cycles/day) 6 WAT 12 WAT 18 WAT 6 WAT 12 WAT 18 WAT 1.8 1 24.0 36.1 37.5 40.3 44.3 44.8 3.6 23.5 34.9 36.9 37.4 44.1 44.7 5.4 27.0 36.8 37.3 38.7 42.9 45.9 Significance ( P<0.05) NS NS NS NS NS NS 1.8 2 22.8 35.3 35.9 39.3 43.5 45.1 3.6 22.6 36.2 36.4 37.6 44.1 46.9 5.4 25.1 36.7 39.4 39.0 43.5 47.3 Significance ( P<0.05) NS NS NS NS NS NS,* Not significant and significant at P<0.05 respectively.

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45 Table 33. Effects of irrigation volumes and frequencies on Strawberry Festival root and shoot dry weight at 25 weeks after transplant. 200809 Season. Volume Frequency Root dry weight Shoot dry weight (L/m/day) (cycles/day) (g) (g) 1.8 1 5.42 33.36 3.6 4.05 29.02 5.4 5.24 41.27 Significance ( P<0.05) NS 1.8 2 3.46 22.82 3.6 5.50 28.57 5.4 4.74 29.30 Significance ( P<0.05) NS NS,* Not significant and significant at P<0.05 respectively.

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46 Table 34. Effects of irrigation volumes and frequencies on Strawberry Festival foliar nutrient concentration at 6 weeks after transplant. 200809 Season. Volume Frequency N P K Ca Mg S Fe Cu B Zn Mn (L/m/day) (cycles/day) (%) (mg/L) 1.8 1 3.14 0.27 1.98 1.33 0.66 0.19 66.25 6.37 40.15 25.11 47.20 3.6 3.11 0.36 2.04 0.68 0.41 0.18 56.69 6.42 31.46 28.94 35.53 5.4 3.00 0.36 2.09 0.59 0.38 0.18 56.92 6.44 30.01 34.63 36.97 Significance ( P<0.05) NS NS NS NS 1.8 2 3.30 0.42 2.11 0.66 0.42 0.19 58.97 6.60 32.97 34.20 36.99 3.6 3.21 0.31 1.88 1.15 0.62 0.18 62.50 5.80 37.68 27.26 38.87 5.4 3.18 0.32 2.05 1.08 0.56 0.18 63.10 6.43 36.64 27.64 42.68 Significance ( P<0.05) NS NS NS NS NS NS NS NS NS,* Not significant and significant at P<0.05 respectively.

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47 Table 35. Effects of irrigation volumes and frequencies on Strawberry Festival foliar nutrient concentration at 12 weeks after transplant. 200809 Season. Volume Frequency N P K Mg Ca S Fe Cu Zn Mn B (L/m/day) (cycles/day) (%) (mg/L) 1.8 1 3.17 0.36 2.45 0.40 0.87 0.21 145.65 12.73 34.53 64.69 51.72 3.6 3.10 0.41 2.52 0.42 0.87 0.22 160.64 13.79 35.94 54.88 41.20 5.4 3.25 0.39 2.38 0.41 0.88 0.21 144.79 12.09 32.66 48.89 37.19 Significance ( P<0.05) NS NS NS NS NS NS NS NS NS NS 1.8 2 3.24 0.40 2.42 0.42 0.90 0.22 155.12 14.31 37.45 55.33 51.91 3.6 3.27 0.41 2.56 0.44 0.95 0.22 161.21 13.75 33.85 44.28 42.95 5.4 3.09 0.35 2.13 0.39 0.80 0.19 126.48 11.10 27.10 35.57 33.91 Significance ( P<0.05) NS NS NS NS NS NS NS NS NS,* Not significant and significant at P<0.05 respectively.

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48 Table 36. Effects of irrigation volumes and frequencies on Strawberry Festival foliar nutrient concentration at 24 weeks after transplant. 200809 Season. Volume Frequency N P K Mg Ca S Zn Mn Fe Cu B (L/m/day) (cycles/day) (%) (mg/L) 1.8 1 2.74 0.26 2.00 0.45 1.67 0.19 34.00 97.33 107.25 10.25 107.75 3.6 2.75 0.29 2.17 0.47 1.61 0.19 30.00 54.50 100.75 10.00 61.50 5.4 2.56 0.30 2.06 0.50 1.68 0.19 28.50 68.00 106.00 10.00 59.50 Significance ( P<0.05) NS NS NS NS NS NS NS NS NS 1.8 2 2.75 0.24 1.86 0.48 1.52 0.19 25.75 67.25 97.25 8.75 77.00 3.6 2.65 0.29 2.37 0.44 1.60 0.19 29.75 67.00 96.75 9.50 85.00 5.4 2.62 0.29 1.97 0.50 1.68 0.19 27.00 54.50 106.25 10.75 61.25 Significance ( P<0.05) NS NS NS NS NS NS NS NS NS,* Not significant and significant at P<0.05 respectively.

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49 Table 37. Effects of irrigation volumes and frequencies on Strawberry Festival fruit quality; prestorage (8 days at 5C) evaluation at14 weeks after transplant. 200809 Season. Volume Frequency Total titratable acidity Soluble solids content External fruit color Firmness (L/m/day) (cycles/day) (%) (Brix) Lightness Chroma hue angle (N) 1.8 1 0.90 7.98 33.12 32.62 29.52 0.60 3.6 0.90 8.23 32.77 34.08 29.20 0.70 5.4 0.90 7.95 32.68 33.57 29.74 0.78 Significance ( P<0.05) NS NS NS NS NS 1.8 2 0.91 8.43 32.78 33.74 29.78 0.68 3.6 0.85 7.75 32.89 32.80 29.67 0.70 5.4 0.82 7.40 32.13 33.34 27.80 0.70 Significance ( P<0.05) NS NS NS NS NS NS NS,* Not significant and significant at P<0.05 respectively.

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50 Table 38. Effects of irrigation volumes and frequencies on Strawberry Festival fruit quality; prestorage (8 days at 5C) evaluation at 18 weeks after transplant. 200809 Season. Volume Frequency Total titratable acidity Soluble solids content External fruit color Firmness (L/m/day) (cycles/day) (%) (Brix) Lightness Chroma hue angle (N) 1.8 1 0.67 8.13 33.62 32.96 29.37 0.60 3.6 0.73 8.88 32.87 32.41 25.02 0.54 5.4 0.71 7.70 33.22 32.90 28.05 0.54 Significance ( P<0.05) NS NS NS NS NS NS 1.8 2 0.73 8.63 32.80 33.27 27.58 0.55 3.6 0.71 8.48 33.38 33.11 29.44 0.53 5.4 0.76 8.50 33.57 32.32 28.87 0.58 Significance ( P<0.05) NS NS NS NS NS NS NS,* Not significant and significant at P<0.05 respectively.

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51 Table 39. Effects of irrigation volumes and frequencies on Strawberry Festival fruit quality; prestorage (8 days at 5C) evaluation at 19 weeks after transplant. 200809 Season. Volume Frequency Total titratable acidity Soluble solids content External fruit color Firmness (L/m/day) (cycles/day) (%) (Brix) Lightness Chroma hue angle (N) 1.8 1 0.82 8.53 32.70 32.52 28.60 0.75 3.6 0.78 7.48 32.48 32.34 27.91 0.80 5.4 0.73 7.95 31.75 32.76 28.49 0.85 Significance ( P<0.05) NS NS NS NS NS NS 1.8 2 0.77 8.80 31.44 32.26 27.85 0.90 3.6 0.78 8.13 31.48 31.94 28.90 0.87 5.4 0.81 8.03 32.88 32.96 28.26 0.95 Significance ( P<0.05) NS NS NS NS NS NS,* Not significant and significant at P<0.05 respectively.

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52 Table 310. Effects of irrigation volumes and frequencies on Strawberry Festival fruit quality prestorage (8 days at 5C) evaluation at 22 weeks after transplant. 200809 Season. Volume Frequency Total titratable acidity Soluble solids content External color Firmness (L/m/day) (cycles/day) (%) (Brix) Lightness Chroma hue angle (N) 1.8 1 0.83 8.88 32.03 27.26 28.89 0.75 3.6 0.60 7.50 29.99 23.11 23.29 0.73 5.4 0.66 7.80 30.74 26.04 27.24 0.57 Significance ( P<0.05) NS NS NS NS 1.8 2 0.70 9.55 32.24 27.67 29.14 0.64 3.6 0.67 7.38 31.42 27.24 24.92 0.73 5.4 0.74 7.55 32.25 28.30 27.25 0.64 Significance ( P<0.05) NS NS NS NS NS NS NS,* Not significant and significant at P<0.05 respectively.

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53 Table 311. Effects of irrigation volumes and frequencies on Strawberry Festival fruit quality post storage (8 days at 5C) of fruit harvested at 19 weeks after transplant. 200809 Season. Volume Frequency Total titratable acidity Soluble solids content External color Firmness (L/m/day) (cycles/day) (%) (Brix) Lightness Chroma hue angle (N) 1.8 1 0.84 8.53 34.11 34.76 26.83 0.76 3.6 0.76 7.48 34.42 36.41 29.51 0.96 5.4 0.76 7.95 33.12 33.55 27.98 0.85 Significance ( P<0.05) NS NS NS NS NS 1.8 2 0.85 8.80 32.16 31.79 26.08 0.96 3.6 0.83 8.13 34.80 36.18 27.21 0.83 5.4 0.79 8.03 33.55 33.62 27.08 0.60 Significance ( P<0.05) NS NS NS NS NS NS,* Not significant and significant at P<0.05 respectively.

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54 Table 312. Effects of irrigation volumes and frequencies on Strawberry Festival fruit quality post storage (8 days at 5C) evaluation of fruit harvested at 22 weeks after transplant. 200809 Season. Volume Frequency Total titratable acidity Soluble solids content External color Firmness (L/m/day) (cycles/day) (%) (Brix) Lightness Chroma hue angle (N) 1.8 1 0.69 8.95 30.54 29.78 32.81 0.70 3.6 0.65 9.10 30.70 30.18 28.96 0.65 5.4 0.72 8.65 31.25 31.50 31.18 0.76 Significance ( P<0.05) NS NS NS NS NS NS 1.8 2 0.72 9.20 30.10 31.78 31.13 0.77 3.6 0.72 9.28 31.27 36.18 29.44 0.60 5.4 0.72 8.93 31.33 33.62 29.89 0.63 Significance ( P<0.05) NS NS NS NS NS,* Not significant and significant at P<0.05 respectively.

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55 A B Figure 31. Effects of irrigation volumes and frequencies on Strawberry Festival A) plant diameter (cm) at 18 weeks after transplant B) shoot dry weight 25 weeks a fter transplant. 200809 Season.

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56 A B Figure 32. Effects of irrigation volumes and frequencies on Strawberry Festival foliar nutrient content at 6 weeks after transplant A) n itrogen (N), B) p hosphorus (P). 2008 09 Season.

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57 A B Figure 33. Effects of irrigation volumes and frequencies on Strawberry Festival foliar content at 6 weeks after transplant A) calcium (Ca) B) m agnesium (Mg). 200809 Season.

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58 A B Figu re 3 4. Effects of irrigation volumes and frequencies on Strawberry Festival foliar content at 6 weeks after transplant A) b oron (B) B) iron (Fe ). 200809 Season.

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59 A B Figure 35. Effects of irrigation volumes and frequencies on Strawberry Festival foliar content at 6 weeks after transplant. A) z inc (Zn) B) m anganese (Mn) 200809 Season.

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60 A B Figure 36. Effects of irrigation volumes and frequencies on Strawberry Festival foliar content at 12 weeks after transplant A) b oron (B), B) z inc (Zn). 2008 09 Season.

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61 Figure 37. Effects of irrigation volumes and frequencies on Strawberry Fes tival m anganese (Mn) foliar content at 12 weeks after transplant. Season 200809.

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62 A B Figure 38. Effects of irrigation volumes and frequencies on Strawberry Festival foliar content at 24 weeks after transplant. A) p hosphorus (P) B) calcium (Ca) 200809 Season.

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63 A B Figure 39. Effects of irrigation volumes and frequencies on Strawberry Festival foliar content at 24 weeks after transplant. A) copper (Cu) B) b oron (B). 200809 Season.

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64 Figure 310. Effects of irrigation volumes and frequencies on Strawberry Festival fruit firmness (N) pre storage (8 days at 5C) at 14 weeks after transplant. 200809 Season.

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65 Figur e 311. Effects of irrigation volumes and frequencies on S trawberry Festival fruit lightness (L*) prestorage (8 days at 5C) at 19 weeks after transplant. 200809 Season.

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66 A B Figure 312. Effects of irrigation volumes and frequencies on Strawberry Festival fruit pre storage (8 days at 5C) analysis at 22 weeks after transplant. A) total tritatable acidity (% citric acid) B) lightness (L*) 200809 Season.

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67 A B Figure 313. Effects of irrigation volumes and frequencies on Strawberry Festival fruit post storage (8 days at 5C) analysis of fruit harvested at 19 weeks after transplant. A) total titratable acidity (% citric acid) B) lightness (L*) 200809 Season.

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68 A B Figure 314. Effects of irrigation volumes and frequencies on Strawberry Festival fruit post storage (8 days at 5C) analysis of fruit harvested at 22 weeks after transplant. A) firmness (N), B) chroma (C*). 200809 Season.

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69 A B Figure 3.15. Effects of irrigation volumes and frequencies on Strawberry Festival early yield (A) and total yield (B). 20082009 Season.

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70 CHAPTER 4 EFFECTS OF IRRIGATION VOLUMES AND FREQUE NCIES ON THE GROWTH, YIELD AND POSTHARVES T QUALITY OF STRAWB ERRY FESTIVAL, FLO RIDA RADIANCE AND WINTE R DAWN ON SANDY SOI LS 2009 10 SEASON Materials and Methods This study was conducted from October 2009 to March 2010 at the Gulf Coast Research and Education Center of the University of Florida, Balm, Florida. The soil at the experimental site is a sandy, siliceous, hyperthermic Oxyaquic Alorthod with <1.5% organic matter and pH of 6.6. Planting beds were preformed with a standard bedder, 71 cm wide at the base, 61 cm wide on the top, and 25 cm high and spaced 120 cm between centers. In August 2009, the soil was fumigated with 350 kg/ha of methyl bromide + chloropicrin (50/50 v/v). After the fumigant injection a singledrip tape line (0.056 L/m/min, T Tape Systems International, San Diego, CA) was buried 5 cm in all plots, regardless of irrigation program, finally the beds were covered with black highdensity polyethylene mul ch. No preplant fertilizer was used. The experimental area was equipped with 15 L/min sprinklers for frost protection and crop establishment. Plant nutrients were supplied to the crop through the drip lines three times per week starting on December 07 wit h a hydraulic injector (Dosatron, Clearwater, FL) following statewide recommendations (Peres et al., 2006), which represented approximately 10.8 L/m/week applied to all the experimental plots. Current recommendations for insect and disease control w ere fol lowed (Peres et al., 2009). Eighteen treatments were tested resulting from combining six irrigation programs and three strawberry cultivars (Strawberry Festival, Florida Radiance and Winter Dawn). The irrigation programs were combinations of three water volumes and two irrigation frequencies. The water volumes were 1.8, 3.6 and 5.4 L/m/day, while the

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71 irrigation frequencies were one and two cycles per day. The experimental design was a split plot design with four replications with the irrigation programs in the main plots and the cultivar in the subplots. Bareroot Winter Dawn and Florida Radiance strawberry transplants from nurseries in Canada were planted on 13 and 14 October 2009, respectively, while the Strawberry Festival transplants were transplanted on 27 October 2009. All the cultivars were transplanted in double rows 38 cm apart, 20 plants per 7.6 m plot with a 1.5 m nontreated buffer zone at the end of each plot. After transplanting, overhead irrigation was used for 8 hours for the first 10 days to ensure plant establishment (the amount of water used was approximately 480,000 L/ha/day). The irrigation volumes were transformed into irrigation times and controlled with electronic timers (Nelson SoloRain, Walla Walla, WA). Treatments receivi ng a single irrigation per day were watered between 9 and 11 am each morning, whereas plots receiving two cycles per day were watered between 3 pm and 4 pm in addition to the morning irrigation. Daily soil water content was determined at 12.7 cm (5 in) wi th a Soil Scout TDR 200 Probe (Spectrum Technologies, Plainfield, Ill.), every other week at 8 am during the strawberry season. Strawberry plant diameter and chlorophyll content readings were taken at 6, 14, and 17 weeks after transplanting (WAT). Plant di ameter was determined using five plants per plot randomly selected and measuring the widest part of the plant. Ten recently mature leaves per plot were randomly selected to measure the chlorophyll content (Chl) with a Chlorophyll meter SPAD 502 (Minolta, R amsey, NJ), an instrument developed to measure the chlorophyll content of leaves as an indirect estimate of the nitrogen status of plants (Martnez and Guiamet, 2004). A numerical SPAD (Soil Plant

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72 Analysis Development) unit, ranging from 0 to 80 is calculated by the chlorophyll meter and used to estimate the Chl content. Foliar nutrient concentrations were determined at 6, 14 and 17 weeks after transplant. A sample of ten recently matured leaves was randomly collected from each experimental plot. Samples were dried at 70C in a forcedair dryer for 48 h. Once dried, leaf samples were ground using a tissue mill (Thomas Scientific Wiley mill, Swedesboro, NJ) and sent for analysis to a commercial lab. Root and shoot dry weight (DW) was determined at the end of the season. Five plants of each experimental plot were removed from the field and dried at 70C in a forcedair dryer for one week. The dry tissue was weighted individually in a precision balance (Mettler Toledo PG2002S, Mettler Toledo, Mark etable strawberry fruit with the attached calyx were harvested twice a week and the weight was recorded for 24 harvests during the season starting on December 07, 2009. Marketable strawberry fruit were defined as fruit over 10 g in weight and physiological ly mature with more than 80% of red skin, free of mechanical defects, insect or disease injury. Early yield was considered as the yield from the first 10 harvests. Postharvest fruit quality (prestorage) was evaluated at harvest dates of January 28 (14 WAT ), February 18 (17 WAT), and March 11 (20 WAT) 2010. Columbus, OH). Fruit from each plot was used for the measurement of external fruit color. It was measured at equator on opposite sides of the fruit with a Minolta CR 400 chroma meter (Minolta, Ramsey, New Jersey). Col or was expressed as lightness (L*), hue angle (h*) and chroma (C*) value. Strawberries from each plot were squeezed and the juice was used to measure soluble solids content (Brix) using a digital refractometer (Atago, Itabashi ku, Tokyo) Fruit from each plot were frozen to be processed the next day to

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73 determine total titratable acidity (TA). Frozen samples were later thawed at room temperature (approximately 22C), then blended in a blender (Waring Commercial blender, Model 7011, Waring Products Inc, Torrington, CT ), and centrifuged at 8490 rpm for 20 min (Sorvall Legend RT and a Sorvall Biofuge stratus, Kendro Laborat ory Products Inc., Newtown, CT ). The obtained juice was filtered and frozen in 20 mL plastic vials for later evaluation. F rozen juice vials were allowed to thaw at room temperature (approximately 22C). Total titratable acidity was measured diluting 6 mL of sample on 50 mL of distilled water, then it was stirred (Metrohm 802 stirrer, Metrohm USA Inc, Westbury, NY) and titrate d (848 Titrino Plus, Metrohm USA Inc, Westbury, NY). TA was calculated with the miliequivalent factor for citric acid (0.064 g per mEq), the major organic acid in strawberries. Between four and ten fruit from each plot were placed in 473 mL clamshells (Hig hland Corporation, Inc., Mulberry, FL) and storage in a cold room at 7C for 8 days. This temperature is notably higher than the recommendation of 0 C, but was selected to represent typical handling conditions and with the purpose to accelerate postharvest decay and determine shelflife. Post storage evaluations included visual quality of the fruit inside the clamshell, for this variable a descriptive test was used to obtain a normal distribution of the data points (Heintz and Kader, 1983). External color (L*, C* and h*), soluble solids content ( Brix) and total titratable acidity were also determined using the same procedures described above for initial quality evaluations ( pre storage) Collected parametric data were analyzed using Statistix 9 software (Analytical Software, Tallahassee, FL) .General linear model procedure (ANOVA split plot analysis) was used to determine the significance (P<0.05) of the individual factors (Irrigation

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74 programs and cultivars), and their interactions. Irrigation programs were separated using standard errors of the treatment means. Results and Discussion 200910 Strawberry Season Environmental C onditions The average environmental conditions from October 2009 to March 2010 from the Florida Automated Weather Network (2010) are shown in Table 41. The total amount of rain was 488 mm during the season (50% in March, 2010). There were four freezing events, on December 29, from January 04 till January 13, 2009, February 14, 15 and 26, 2010, (daily averages on Appendix A).Water content of the soil used at the experimental site was between 10% and 14% during the strawberry season (Figure 41), that range can be considered as field capacity in sandy soils. Soil water content higher than 10% means that there was enough water to satisfy the plant water needs. Plant Diameter and Chlorophyll C ontent There were no significant differences in plant diameter among the irrigation programs and cultivars at 6 WAT, ranging from 22.4 to 24.3 cm. At 14 and 17 WAT, there was a significant difference among cultivars, ranging between 28.4 and 33.8 cm at 14 WAT and between 25.7 and 31.0 cm at 17 WAT, but not among irrigation programs at 14 and 17 WAT (Table 42). Strawberry Festival had the highest plant diameter 14 WAT, 33.8 cm, followed by Winter Dawn, 31.8 cm while Florida Radiance had the smallest diameter 14 and 17 WAT, 28.4 and 25.7 cm respectively. Plant diameter among irrigation programs ranged from 22.4 and 24.3 cm 6 WAT, from 30.6 and 31.8 cm 14 WAT and from 28.3 to 29.7 cm 17 WAT. There was no interaction irrigation program x cultivar, significant differences were found in Chl content among strawberry cultivars at 6, 14 and 17 WAT (Table 43). The first evaluation at 6 WAT showed that

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75 Winter Dawn had the highest SPAD value of 46.6, followed by Florida Radiance and Strawberry Festival with values of 45.3 and 41.0. The second and third evaluation showed the same pattern obtained in the first evaluation, the range of the second evaluation was between 46.2 and 48.9 and for the third evaluation was between 43.7 and 48.7. There were no significant differences among irrigation programs; Chl content ranged between 43.9 and 44.9 at 6 WAT, between 46.9 and 48.2 at 14 WAT and between 45.4 and 46.4 at 17 WAT. There was no effect of irrigation program x cultivar. Root and Shoot Dry W eight There were no significant differences among the irrigation programs for root dry weight; the range was between 5.08 and 5.7 grams (Table 44). There were significant differences among the strawberry cultivars. Winter D awn had the highest root dry weight with a value of 6.33 g, followed by Strawberry Festival with a value of 5.55 g, the lowest value (4.88 g) was for Florida Radiance. There were effects of the irrigation program x cultivar for shoot dry weight (Table 4 5). The highest value of shoot dry weight was for Strawberry Festival from plots irrigated with 1.8 L/m/day in two cycles per day, while the lowest values were for Florida Radiance irrigated with the six programs. Foliar Nutrient C oncentrations Foliar analysis at 6, 14 and 17 WAT showed that all nutrients were in adequate range based on the values described by Peres et al. (2009). There were no effects of irrigation program x cultivar. There were no significant differences among irrigation programs f or nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), iron (Fe), boron (B), manganese (Mn), zinc (Zn), potassium (K), sulfur (S) and copper (Cu) but there were among cultivars for N, K, Ca, Mg, S, Zn and Mn (Table 4 6). For N and Mg

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76 Strawberry Festival had the lowest values and Winter Dawn the highest, ranging between 3.14% and 3.43% for N and 0.43% and 0.49% for Magnesium. Florida Radiance had the highest percentage of K and Ca, and for S and Zn the order from lowest to highest was Winter D awn
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77 P (0.44%) and B (47.46 mg/L). Florida Radiance had the lowest values for P, B, and Mn, the values were 0.40%, 39.58 and 60.63 mg/L, respectively; intermediate values for Ca (1.01%), Mg (0.45%), and Zn (28.38 mg/L), and it had the highest values for N (3.61%), K(2.43%), S (0.23%), Fe (71.42 mg/L) and Cu (8.67 mg/L). Finally, Winter Dawn had the lowest values for S (0.21%), Fe (64.21 mg/L), Cu (8.00 mg/L), and Zn (25.92 mg/L), intermediate values for N (3.33%), K (2.30%), P (0.43%), and B (40.17 mg/L) and the highest values for Ca, Mg and Mn with values of 1.02%, 0.47% and 91.63 mg/L, respectively. In the foliar analysis at17 WAT (Table 48) there were significant differences among the irrigation programs for N, P, K, S, B, Zn and Mn. For N 3.6 L/m/day in one cycle/day had the highest content, 3.41%, while the lowest value was for 5.4 L/m/day in one cycle per day with a value of 3.19%. The volumes of 1.8 and 3.6 L/m/day in one and two cycles/day had the highest % of P with values ranging from 0.44% to 0.45%. The highest K content was in leaves from plots irrigated with 5.4 L/m/day in two cycles per day (2.41%) while the lowest was for plants irrigated with the same volume but in one cycle/day (2.17%). The irrigation volume of 5.4 L/m/day applied in one and two cycles/day had the lowest values for S (0.20% and 0.20%) and B (39.69 and 39.85 mg/L). The highest Zn concentration was obtained in plants irrigated with 3.6 L/m/day in one cycle per day with a value of 27.21 mg/L, while the lowest was for the irrigation program of 5.4 L/m/day in two cycles per day with a value of 23.65 mg/L. For Mn, the program of 3.6 L/m/day in two cycles per day with a value of 78.06 mg/L was the l owest; the highest value was 112.17 mg/L for the program on 1.8 L/m/day applied in one cycle per day. There were significant differences between cultivars for all the nutrients

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78 analyzed. For N and K, Florida Radiance had the highest values, 3.49% (N) and 2.42% (K), followed by Winter Dawn with values of 3.33% (N) and 2.31% (K) and the lowest values were for Strawberry Festival, 3.14% (N) and 0.86% (K). The P concentration for Winter Dawn was 0.48%, while for the other two cultivars was 0.40%. Flori da Radiance had the highest % of Ca, 1.08%, followed by Winter Dawn, 0.97%, and Strawberry Festival 0.86%. For Mg, the order from highest to lowest was Winter Dawn> Florida Radiance> Strawberry Festival with values of 0.44%, 0.41% and 0.37% res pectively. Florida Radiance had the highest values for S, Fe and Cu content with values of 0.22 %, 74.67 and 9.88 mg/L, Winter Dawn had values of 0.20% (S), 64.74 mg/L (Fe) and 8.22 (Cu), and Strawberry Festival had values of 0.20% (S), 63.56 mg/L (F e) and 8.46 mg/L (Cu). Strawberry Festival had the highest value for B (51.38 mg/L), followed by Florida Radiance and Winter Dawn with values of 42.22 and 40.97 mg/L, respectively. The highest values for Zn were Florida Radiance (27.06 mg/L) and S trawberry Festival (25.58 mg/L), Winter Dawn was the lowest with a value of 23.64 mg/L. Finally, for Mn Winter Dawn and Strawberry Festival had the highest values of 111.98 and 101.12 mg/L, respectively; while Florida Radiance had the lowest value of 70.56 mg/L. There was no effect of program x cultivar. Pre storage Strawberry Fruit Q uality There w ere no significant differences i n total titratable acidity, soluble solids content, and external color expressed as L*, C* and h* among the irrigation programs in the prestorage evaluation at14 WAT (Table 49). TA ranged between 1.30% and 1.33%, for soluble solids content it ranged from 7.65 to 8.44Brix, for L* it ranged between 35.02 and 36.07, C* ranged between 39.73 and 40.97 and h* ranged from 27.5 1 to 29.47. However, t here were significant differences among the strawberry

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79 cultivars. For TA, Strawberry Festival had the lowest value (1.30%) while Florida Radiance had a value of 1.38% and Winter Dawn a value of 1.52%. The soluble solids content was higher for Strawberry Festival (9.16Brix) followed by Florida Radiance (7.89Brix) and Winter Dawn (6.53Brix). For external color, L* was higher for Strawberry Festival with a value of 36.82, followed by Winter Dawn with a value of 35.52 and Florida Radiance with a value of 34.69; C* values were 39.13, 40.36 and 40.49 for Strawberry Festival, Florida Radiance and Winter Dawn, respectively. Hue angle was higher for Strawberry Festival with a value of 31.66, followed by Winter Dawn w ith a value of 28.09 and Florida Radiance with a value of 26.41. For TA, soluble solids content, L*, and h* there were no significant differences among the treatments in the prestorage evaluation at 17 WAT (Table 410). The range for TA was between 1.06% and 1.13%, for soluble solids content between 6.71Brix and 7.13Brix, and for external color between 34.96 and 35.57 for L*, between 41.19 and 41.67 for C*and from 27.99 to 29.45 for h*. There were significant differences among strawberry cultivars. Strawberry Festival and Florida Radiance had values of TA of 1.18% and 0.93% while Winter Dawn had the highest value, 1.20%. The soluble solids contents were 6.42Brix and 6.79Brix for Florida Radiance and Winter Dawn and 7.64Brix for Strawberr y Festival. Values of L* were 33.78, 35.22 and 37.29 for Florida Radiance, Strawberry Festival and Winter Dawn, respectively. Strawberry Festival and Florida Radiance had C* values of 39.49 and 39.87, while Winter Dawn had a value of 45.01. Hu e angle was low for Florida Radiance (27.45) and it was higher for Winter Dawn and Strawberry Festival with values of 29.15 and 30.25, respectively,

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80 meaning that Florida Radiance had a more red color than the other two cultivars. There were no effects of irrigation programs x cultivar. There were no significant differences among the irrigation programs for total titratable acidity, soluble solids content, L*, C*, and h* at 20 WAT (Table 411). TA ranged from 0.99% to 1.05% and the soluble solids co ntent from 7.59Brix to 8.22Brix. It ranged between 33.02 and 33.99 for L*, between 37.58 and 38.90 for C* and from 24.55 to 26.70 for h*. There were significant differences among cultivars. Strawberry Festival and Winter Dawn had values of TA of 1.07% and 1.08%, while Florida Radiance had a value of 0.92%. Strawberry Festival had the highest value of soluble solids content (9.03Brix) whereas Florida Radiance and Winter Dawn had values of 7.52Brix and 6.99Brix. For external color variables Strawberry Festival and Winter Dawn had higher values of L*, 34.27 and 34.19, than the Florida Radiance value of 32.75. Winter Dawn had a value of 40.11, the highest for C*, followed by Florida Radiance with a value of 38.83 and Strawberry Festiv al with a value of 36.56. For h*, the highest value was for Strawberry Festival (27.47) followed by Winter Dawn (25.82) and Florida Radiance (23.77). There were no effects of irrigation program x cultivar. Post storage Strawberry Fruit Q uality Post storage analysis included TA, soluble solids content (Brix), external color (L*, C*and h*) and visual quality at 14 WAT (Table 412). There were no significant differences among irrigation programs for any of the variables evaluated. The range for TA wa s between 1.26% and 1.33%, for soluble solids content between 6.73Brix and 7.12Brix. L* of fruit ranged from 32.93 to 34.02, C* ranged between 39.66 and 40.98 and h* had values that ranged from 27.11 to 29.65. Visual quality of the fruit had values betw een 6.18 and 6.96. There were significant differences between the strawberry

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81 cultivars in all variables evaluated except for visual quality, which ranged from 6.50 to 6.83. Florida Radiance had the lowest value of acidity (1.04%) followed by Strawberry Festival with a value of 1.37% and the cultivar with the highest value of acidity was Winter Dawn (1.50%). For soluble solids content, Strawberry Festival had the highest value, 7.95Brix, followed by Florida Radiance and Winter Dawn with values o f 6.44Brix and 6.32Brix. External color of Strawberry Festival had a L* value of 34.32, followed by Winter Dawn with a value of 33.13 and Florida Radiance with a value of 32.91. C* had values of 41.31, 41.25 for Winter Dawn and Florida Radiance respectively, and Strawberry Festival had a value of 38.31. Hue angle was higher for Strawberry Festival (29.98), followed by Winter Dawn with a value of 28.37 and a value of 26.64 for Florida Radiance. There were no effects of irrigation program x cultivar. At 17 WAT there were significant differences among irrigation programs for L* and h* but not for TA, soluble solids content and visual quality (Table 413). For L*, irrigation programs of 1.8 and 5.4 L/m/day in two cycles/day had the lowest v alues, 32.90 and 32.83 respectively and the highest value was for the irrigation program of 3.6 L/m/day in two cycles/day with a L* value of 34.03. Programs of 1.8, 3.6 and 5.4 L/m/day in one cycle/day had values of 33.73, 33.10 and 33.64, respectively. Hue angle was higher for the program of 3.6 L/m/day in two cycles/day (26.87), followed by 5.4, 1.8 and 3.6 L/m/day in one cycle/day with values of 26.66, 26.01 and 25.72, respectively. The lowest values were 25.35 and 25.28 for the programs of 5.4 and 1.8 L /m/day in two cycles per day. TA ranged from 1.11% to 1.19%, the soluble solids content had values within a range of 8.29Brix and 8.53Brix, the range of the visual

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82 quality values was between 5.84 and 6.56. There were significant differences among cultiva rs for TA, soluble solids content, L*, h* and visual quality. For TA, Winter Dawn and Strawberry Festival had values of 1.23% and 1.19% and the lowest value was for Florida Radiance with a 1.03% value. Soluble solids content were higher for Strawberry Festival (9.32Brix), followed by Florida Radiance and Winter Dawn with values of 7.98Brix and 8.07Brix, respectively. The value of L* was higher for Winter Dawn (34.80), followed by Strawberry Festival (33.69) and Florida Radiance with a value of 31.63. Hue angle was higher for Strawberry Festival (28.29) followed by Winter Dawn (25.59) and Florida Radiance (24.07). Visual quality of Strawberry Festival (6.74) and Florida Radiance (6.46) were higher than Winter Dawn (5.22). The re was an effect of irrigation program x cultivar for C* (Table 414) but not for the rest of the variables analyzed. The higher values of C* were for the cultivar Winter Dawn irrigated with 1.8, 3.6 and 5.4 L/m/day in one cycle/day with values of 43.06, 41.02, and 41.73, respectively and 3.6 and 5.4 L/m/day in two cycle/day with values of 42.72 and 41.25. The lowest values were for Strawberry Festival for 1.8 L/m/day in one cycle/day and 3.6 L/m/day in two cycles/day with values of 36.75 and 36.53 and Florida Radiance with values of 36.1 and 35.86 for the programs of 1.8 and 3.6 L/m/day in one cycle per day. There were significant differences for the irrigation programs for visual quality but not for TA, soluble solids, L*, C* and h* at 20 WAT (Table 4 15). TA ranged between 0.97% and 1.03%, for soluble solids content the values had a range from 8.00Brix to 8.50%, L* ranged between 31.37 and 33.08, C* ranged from 37.89 to 39.45 and h* had a range from 23.95 to 26.41. Visual quality was higher for 1. 8 L/m/day in one cycle/day

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83 while the lowest was for the program of 3.6 L/m/day in two cycles per day. There were significant differences among cultivars for the variables evaluated but not for visual quality, which had a range from 6.92 to 7.02. Strawberr y Festival had the highest TA with a value of 1.05%, followed by Winter Dawn with a value of 1.08% and Florida Radiance had the lowest value of 0.89%. Strawberry Festival had also the highest value of soluble solids content (9.24Brix) while Florida Radiance and Winter Dawn had values of 7.88Brix and 7.61Brix. For external color, Strawberry Festival and Winter Dawn had the highest values of L*, 32.87 and 32.48, respectively, followed by Florida Radiance with a value of 31.07. C* value for Winter Dawn was the highest (40.14) and Strawberry Festival and Florida Radiance had values of 37.62 and 38.50. Strawberry Festival had the highest h with a value of 27.72, followed by Winter Dawn (25.60) and Florida Radiance with a value of 22.97. There were no effects of irrigation program x cultivar. Early and Total Y ield For early and total yield there were no significant differences among the irrigation programs (Table 416). For early yields the range was between 2.31 and 2.52 t/ha while the total yields ranged from 10.30 to 11.30 t/ha. There were significant differences among the cultivars for both early and total yield. The highest early yield was obtained by Florida Radiance, followed by Strawberry Festival with a value of 2.26 t/h a and Winter Dawn with an early yield of 2.14 t/ha. Although Winter Dawn had the lowest early yield, it had the highest total yield for the season 200910, with a value of 13.40 t/ha. Strawberry Festival had a total yield of 10.13 t/ha and Florida R adiance had the lowest total yield, 8.73 t/ha.

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84 The 200910 strawberry season for was colder than the 200809 strawberry season in west central Florida. According to Florida Automatic Weather Network (2010), between December 2009 and January 2010there were 14 days of temperatures below 0C. The sprinklers are usually turned on when the temperatures reach 2 C, which meant approximately 24 days under freeze protection, where the strawberry plants were covered with a layer of ice. Some consequences of this weather conditions were thousands of gallons of water spent in freeze protection, crop losses and inability to harvest. A published critical temperature for strawberry injury in bloom and small fruit is 2 C (Michigan State University Extension, 2004), temperature reached 7 times in a time frame of 10 days. The results of the present research might have been affected by these freeze events; the air and soil temperatures were lower than the first season and the large amount of days under freeze protection might have slowed the strawberry plants metabolism. Durner and Poling (1987) described that cluster production on Earliglow was enhanced with 50 hours of chilling (4.4C) but with 150 hours at the same temperature it was delayed by 3 weeks. It was found that cooler day/night temperatures (18/12C) shifted biomass from leaves to roots but it also was a good temperature for fruit growth (Wang and Camp, 2000). Soil temperature can affect the growth of the roots, initiation of branching, orientation and direction of growth but genotypic differences between cultivars can also be found (Kaspar and Bland, 1992). The results of the present research showed that irrigation programs did not influence the root weight but there were differences among the cultivars, Winter Dawn had in the order of 33% more dry root weight than Florida Radiance, it also had more chlorophyll content through the season, which meant a good nitrogen status.

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85 Even though the plant tissue analysis showed that the strawberry plant nutrient conte nt of all the irrigation programs and cultivars were between normal ranges, Winter Dawn had the highest total yield and that might also be related to the high root dry weight, these roots might have supported the cold weather and sustained the plant thro ugh the following months. Shokaeva ( 2008) reported that the effect of freeze on yield can be correlated to plant growth and root damage. I t is possible that Winter Dawn roots were less damaged after the freezing events. In terms of plant growth, Macias R odriguez et al. (2002) reported that strawberry crowns are a high source of soluble and storage carbohydrates, important for growth and fruit development. These storage carbohydrates might have supported the plant growth and strawberry fruit production aft er the cold weather in January and February. As Fernandez et al. (2001) mentioned, after allocating their resources to roots, crowns, and leaves the strawberry plant shift the resources to vegetative and reproductive plant parts However, as a consequence of the low temperatures, growing was not as fast as it should have been or the plants did not grow enough to be able to storage an adequate amount of carbohydrates to be shifted for fruit development. Florida Radiance had the lowest root and shoot dry weight regardless of irrigation program. Probably, as a result of those values it had the lowest total yield. Nonetheless, it had the highest early yield of 2.72 t/ha which in terms of value represents more income for a strawberry grower than the early yields of Winter Dawn and Strawberry Festival. In general, prestorage evaluation of strawberry fruits was not affected by irrigation programs but it was affected by the cultivars during the second season. As mentioned by Chandl er (2009), the flavor of Winter Dawn is slightly acidic, it had the highest

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86 values of titratable acidity and generally the lowest values of soluble solids content through the season in contrast with Strawberry Festival that had lower titratable acidity and higher values of soluble solids content. Fruit external color fruit was different among cultivars in most of the evaluations, but it did not always follow the same order Winter Dawn had the highest values of chroma at the end the season (17 and 20 WAT) in both pre storage and post storage evaluations, meaning that Winter Dawn fruit had a more vivid color. The lower the hue angle the redder the strawberry fruit, and those low values corresponded to Florida Radiance most of the time in addition to low values of lightness. In terms of quality the cultivars had on average similar values after one week of storage at 7C except for the evaluation 17 WAT, where Winter Dawn had the lowest quality. According to Florida Automatic Weather Network (2010), the average evapotranspiration during the 20092010 strawberry season was 2.5 L/m/day, it was lower than the 20082009 strawberry season. Probably the irrigation program of 1.8 L/m/day in one or two cycles/day provided enough water for growth and development of the strawberry plants, without affecting nutrient absorption and postharvest quality, and even with these irrigation programs soil water content was not lower than 10%, meaning that the soil was on field capacity for the strawberry season. However, as discussed before, the results obtained in the present research could have been strongly influence d by the particular weather conditions. Further research needs to be done to corroborate if an irrigation volume of 1.8 L/m/day can be enough to supply the w ater needs of the crop without reducing growth, yield and postharvest quality

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87 Table 41. Average environmental conditions from October 2009 to March 2010 from FAWNMonth weather report for Balm, Florida. Air Temperature (C) Soil Temperature (C) Rain (mm) Relative humidity (%) Solar irradiation (w/m2 ) Avg Min Max Avg Min Max October 24.3 7.5 37.4 25.3 21.7 27.8 35.6 79 187.5 November 19.1 4.6 29.5 22.2 18.0 25.9 46.5 80 156.6 December 16.7 0.9 29.4 19.1 15.3 21.9 63.0 82 113.4 January 11.7 4.5 28.0 15.4 10.6 19.2 81.1 76 145.3 February 12.1 0.6 26.1 15.5 12.4 18.8 56.4 74 161.5 March 15.1 0.5 27.9 16.7 13.0 20.1 156.3 73 218.3 Florida Automated Weather Network

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88 Table 42. Effects of irrigation volumes and frequencies on strawberry plant diameter at 6, 14, and 17 weeks after transplant (WAT). 200910 Season. Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively. Volume Frequency Plant Diameter (cm) (L/m/day) (cycles/day) 6 WAT 14 WAT 17 WAT 1.8 1 24.3 31.1 28.3 3.6 23.3 31.8 29.7 5.4 22.4 30.6 27.9 1.8 2 23.0 31.2 29.7 3.6 24.2 31.6 29.4 5.4 22.7 31.6 29.6 Significance ( P<0.05) NS NS NS Cultivars 'Strawberry Festival' 22.8 33.8 c 30.7 b 'Florida Radiance' 23.5 28.4 a 25.7 a 'Winter Dawn' 23.6 31.8 b 31.0 b Significance ( P<0.05) NS

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89 Table 43. Effects of irrigation volumes and frequencies on strawberry leaf chlorophyll content at 6, 14 and 17 weeks after transplant (WAT). 200809 Season. Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively. Volume Frequency Chlorophyll content (SPAD value) (L/m/day) (cycles/day) 6 WAT 14 WAT 17 WAT 1.8 1 44.2 47.5 45.6 3.6 43.9 47.3 46.2 5.4 44.6 46.9 44.8 1.8 2 44.3 47.3 46.4 3.6 44.9 47.3 46.2 5.4 43.9 48.2 45.4 Significance ( P<0.05) NS NS NS Cultivars 'Strawberry Festival' 41.0 a 46.2 a 43.7 a 'Florida Radiance' 45.3 b 47.2 b 44.8 b 'Winter Dawn' 46.6 c 48.9 c 48.7 c Significance ( P <0.05)

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90 Table 44. Effects of irrigation volumes and frequencies on strawberry root dry weight at 22 weeks after transplant. 200910 Season. Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively. Irrigation Programs Root dry weight Volume Frequency (L/m/day) (cycles/day) (g) 1.8 1 5.08 3.6 5.47 5.4 5.33 1.8 2 5.70 3.6 5.18 5.4 5.36 Significance ( P<0.05) NS Cultivars 'Strawberry Festival' 5.55 b 'Florida Radiance' 4.18 c 'Winter Dawn' 6.33 a Significance ( P<0.05)

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91 Table 45. Effects of irrigation volumes and frequencies on strawberry shoot dry weight at 22 weeks after transplant. 200910 Season. Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively. Cultivar Volume Frequency Shoot dry weight (L/m/day) (cycles/day) (g) 'Strawberry Festival' 1.8 1 23.27 cde 3.6 26.34 bcd 5.4 20.84 de 1.8 2 32.44 a 3.6 27.30 abc 5.4 22.63 cde 'Florida Radiance' 1.8 1 10.37 f 3.6 11.73 f 5.4 11.51 f 1.8 2 13.34 f 3.6 10.12 f 5.4 10.52 f 'Winter Dawn' 1.8 1 23.42 cde 3.6 29.35 ab 5.4 20.81 de 1.8 2 20.47 e 3.6 22.73 cde 5.4 23.26 cde Significance ( P<0.05)

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92 Table 46. Effects of irrigation volumes and frequencies on strawberry foliar nutrient concentration at 6 weeks after trans plant. 200910 Season. Volume Frequency N P K Ca Mg S Fe Cu B Zn Mn (L/m/day) (cycles/day) (%) (mg/L) 1.8 1 3.25 0.38 2.84 0.85 0.48 0.20 63.67 6.08 34.92 34.67 54.42 3.6 3.38 0.43 3.05 0.81 0.46 0.21 65.17 6.17 41.42 39.17 55.83 5.4 3.32 0.39 2.87 0.80 0.47 0.20 61.25 4.50 34.67 38.75 53.17 1.8 2 3.24 0.48 2.99 0.84 0.47 0.21 65.00 8.08 38.08 36.25 54.75 3.6 3.32 0.40 2.99 0.80 0.46 0.21 68.33 7.17 40.25 37.67 55.92 5.4 3.39 0.39 2.91 0.79 0.47 0.21 68.75 7.50 40.92 37.83 59.08 Significance ( P<0.05) NS NS NS NS NS NS NS NS NS NS NS Cultivar 'Strawberry Festival' 3.10 b 0.43 2.90 b 0.76 b 0.43 b 0.21 a 66.92 7.04 38.00 42.00 a 49.00 b 'Florida Radiance' 3.40 a 0.41 3.00 a 0.85 a 0.48 a 0.21 a 65.46 6.75 39.42 35.00 b 48.00 b 'Winter Dawn' 3.40 a 0.40 2.90 b 0.84 a 0.49 a 0.20 b 63.71 5.96 37.71 35.00 b 70.00 a Significance ( P<0.05) NS * NS NS NS Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively.

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93 Table 47. Effects of irrigation volumes and frequencies on strawberry foliar nutrient concentration at 14 weeks after transplant. 200910 Season. Volume Frequency N P K Ca Mg S Fe Cu B Zn Mn (L/m/day) (cycles/day) (%) (mg/L) 1.8 1 3.41 0.44 a 2.40 a 0.99 0.45 0.22 ab 68.42 8.75 46.00 a 28.92 89.00 a 3.6 3.45 0.42 a 2.40 ab 0.96 0.44 0.22 a 68.50 8.42 43.00 b 28.00 75.00 bc 5.4 3.21 0.40 b 2.10 c 1.00 0.46 0.21 c 68.75 8.33 38.00 d 29.58 80.00 ab 1.8 2 3.38 0.43 a 2.30 b 0.99 0.46 0.22 abc 67.25 8.42 45.00 a 28.00 75.00 bc 3.6 3.39 0.42 a 2.40 ab 0.97 0.44 0.22 a 66.75 8.25 43.00 b 27.17 69.00 c 5.4 3.39 0.42 a 2.40 ab 0.95 0.45 0.21 bc 66.25 8.08 40.00 c 27.17 84.00 ab Significance ( P<0.05 ) NS NS NS NS NS NS Cultivar 'Strawberry Festival' 3.20 c 0.44 a 2.30 b 0.90 b 0.43 c 0.22 b 67.00 c 8.40 a 47.00 a 30.00 a 84.00 b 'Florida Radiance' 3.60 a 0.40 b 2.40 a 1.01 a 0.45 b 0.23 a 71.00 a 8.70 a 40.00 b 28.00 a 61.00 c 'Winter Dawn' 3.30 b 0.43 a 2.30 b 1.02 a 0.47 a 0.21 c 64.00 c 8.00 b 40.00 b 26.00 b 92.00 a Significance ( P<0.05 ) * * Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively.

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94 Table 48. Effects of irrigation volumes and frequencies on strawberry foliar nutrient concentration at 17 weeks after transplant. 200910 Season. Volume Frequency N P K Ca Mg S Fe Cu B Zn Mn (L/m/day) (cycles/day) (%) (mg/L) 1.8 1 3.3 ab 0.44 a 2.26 bc 0.97 0.40 0.21 a 65.95 9.22 46.00 a 26.00 ab 112.00 a 3.6 3.4 a 0.45 a 2.28 bc 1.04 0.41 0.21 a 73.05 9.23 47.00 a 27.00 a 101.00 ab 5.4 3.2 c 0.39 c 2.17 c 0.98 0.42 0.20 c 64.84 8.86 40.00 b 25.00 bc 90.00 bc 1.8 2 3.3 b 0.44 ab 2.32 ab 0.96 0.41 0.21 b 66.68 8.49 50.00 a 26.00 ab 95.00 abc 3.6 3.4 ab 0.44 a 2.36 ab 0.95 0.40 0.21 ab 69.10 8.95 47.00 a 24.00 bc 78.00 c 5.4 3.3 b 0.42 b 2.41 a 0.92 0.40 0.20 bc 66.31 8.37 40.00 b 24.00 c 92.00 bc Significance ( P<0.05 ) NS NS NS NS Cultivar 'Strawberry Festival' 3.10 c 0.40 b 2.20 c 0.86 c 0.37 c 0.20 b 64.00 b 8.40 b 51.00 a 26.00 a 101.00 a 'Florida Radiance' 3.50 a 0.40 b 2.40 a 1.08 a 0.41 b 0.22 a 75.00 a 9.80 a 42.00 b 27.00 a 71.00 b 'Winter Dawn' 3.3 0b 0.50 a 2.30 b 0.97 b 0.44 a 0.20 b 65.00 b 8.20 b 41.00 b 24.00 b 112.00 a Significance ( P<0.05 ) * * Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively.

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95 Table 49. Effects of irrigation volumes and frequencies on strawberry fruit quality prestorage (8 days at 7C) evaluation at 14 weeks after transplant. 200910 Season. Volume Frequency Total titratable acidity Soluble solids content External color (L/m/day) (cycles/day) (%) (Brix) Lightness Chroma hue angle 1.8 1 1.31 7.69 35.79 40.00 28.87 3.6 1.32 8.44 35.75 40.06 29.47 5.4 1.33 7.49 35.93 40.97 28.83 1.8 2 1.30 8.01 35.50 39.73 28.45 3.6 1.31 7.65 36.07 40.01 29.21 5.4 1.31 7.89 35.02 39.21 27.51 Significance ( P<0.05) NS NS NS NS NS Cultivar 'Strawberry Festival' 1.04 c 9.16 a 36.82 a 39.13 b 31.66 a 'Florida Radiance' 1.38 b 7.89 b 34.69 c 40.36 a 26.41 c 'Winter Dawn' 1.52 a 6.53 c 35.52 b 40.49 a 28.09 b Significance ( P<0.05) * Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively.

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96 Table 410. Effects of irrigation volumes and frequencies on strawberry fruit quality prestorage (8 days at 7C) evaluation at 17 weeks after transplant. 200910 Season. Volume Frequency Total titratable acidity Soluble solids content External color (L/m/day) (cycles/day) (%) (Brix) Lightness Chroma hue angle 1.8 1 1.13 7.03 35.57 41.67 28.88 3.6 1.10 6.71 35.62 41.51 29.27 5.4 1.06 7.13 35.85 41.55 29.45 1.8 2 1.11 6.94 34.96 41.21 27.99 3.6 1.10 7.02 35.17 41.59 28.92 5.4 1.13 6.86 35.40 41.19 29.19 Significance ( P<0.05) NS NS NS NS NS Cultivar 'Strawberry Festival' 1.18 a 7.64 a 35.22 b 39.49 b 30.25 a 'Florida Radiance' 0.93 a 6.42 b 33.78 c 39.87 b 27.45 b 'Winter Dawn' 1.20 b 6.79 b 37.29 a 45.01 a 29.15 a Significance ( P<0.05) * Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively.

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9 7 Table 411. Effects of irrigation volumes and frequencies on strawberry fruit quality prestorage (8 days at 7C) evaluation at 20 weeks after transplant. 200910 Season. Volume Frequency Total titratable acidity Soluble solids content External color (L/m/day) (cycles/day) (%) (Brix) Lightness Chroma hue angle 1.8 1 1.00 7.59 33.02 37.58 24.55 3.6 1.04 7.86 33.80 38.51 26.26 5.4 0.99 7.67 33.78 38.76 25.58 1.8 2 1.04 7.99 33.69 38.90 25.17 3.6 1.05 8.22 34.12 38.88 26.70 5.4 1.02 7.75 33.99 38.39 25.86 Significance ( P<0.05) NS NS NS NS NS Cultivar 'Strawberry Festival' 1.07 a 9.03 a 34.27 a 36.56 c 27.47 a 'Florida Radiance' 0.92 b 7.52 b 32.75 b 38.83 b 23.77 c 'Winter Dawn' 1.08 a 6.99 b 34.19 a 40.11 a 25.82 b Significance ( P<0.05) * Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively.

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98 Table 412. Effects of irrigation volumes and frequencies on strawberry fruit quality post storage (8 days at 7C) evaluation at 14 weeks after transplant. 20092010 Season. Volume Frequency Total titratable acidity Soluble solids content External color Visual quality (L/m/day) (cycles/day) (%) (Brix) Lightness Chroma hue angle 1.8 1 1.30 6.79 33.24 40.32 28.46 6.64 3.6 1.32 6.73 33.80 40.98 29.65 6.96 5.4 1.26 7.11 33.11 40.60 27.64 6.82 1.8 2 1.31 7.12 34.02 39.66 28.37 6.65 3.6 1.33 6.88 33.63 40.24 28.76 6.56 5.4 1.30 6.82 32.93 39.95 27.11 6.18 Significance ( P<0.05) NS NS NS NS NS NS Cultivar 'Strawberry Festival' 1.37 b 7.95 a 34.32 a 38.31 b 29.98 a 6.58 'Florida Radiance' 1.04 c 6.44 b 32.91 b 41.31 a 26.64 c 6.83 'Winter Dawn' 1.50 a 6.32 b 33.13 b 41.25 a 28.37 b 6.50 Significance ( P<0.05) * NS Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively.

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99 Table 413. Effects of irrigation volumes and frequencies on strawberry fruit quality post storage (8 days at 7C) evaluation at 17 weeks after transplant. 20092010 Season. Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively. Volume Frequency To tal titratable acidity Soluble solids content External color Visual quality (L/m/day) (cycles/day) (%) (Brix) Lightness hue angle 1.8 1 1.15 8.29 33.73 ab 26.01 abc 6.11 3.6 1.11 8.53 33.10 ab 25.72 bc 6.45 5.4 1.14 8.41 33.64 ab 26.66 ab 6.03 1.8 2 1.13 8.52 32.90 b 25.28 c 5.85 3.6 1.17 8.36 34.03 a 26.87 a 6.56 5.4 1.19 8.64 32.83 b 25.35 c 5.84 Significance ( P<0.05) NS NS NS Cultivar 'Strawberry Festival' 1.19 a 9.32 a 33.69 a 28.29 a 6.74 a 'Florida Radiance' 1.03 b 7.98 b 31.63 c 24.07 c 6.46 a 'Winter Dawn' 1.23 a 8.07 b 34.80 a 25.59 b 5.22 b Significance ( P<0.05) *

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100 T able 414. Effects of irrigation volumes and frequencies on strawberry chroma post storage (8 days at 7C) at 17 weeks after transplant 200910 Season. Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively. Cultivar Volume Frequency Chroma (L/m/day) (cycles/day) 'Strawberry Festival' 1.8 1 36.75 d 3.6 37.36 cd 5.4 37.13 cd 1.8 2 37.06 d 3.6 36.52 d 5.4 37.35 cd 'Florida Radiance' 1.8 1 35.86 d 3.6 36.09 d 5.4 37.58 cd 1.8 2 37.67 cd 3.6 39.70 bc 5.4 37.15 cd 'Winter Dawn' 1.8 1 43.06 a 3.6 41.01 ab 5.4 41.73 ab 1.8 2 39.67 bc 3.6 42.72 a 5.4 41.25 ab Significance ( P<0.05)

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101 Table 415. Effects of irrigation volumes and frequencies on strawberry fruit quality post storage (8 days at 7C) evaluation at 20 weeks after transplant. 20092010 Season. Volume Frequency Total titratable acidity Soluble solids content External color Visual quality (L/m/day) (cycles/day) (%) (Brix) Lightness Chroma hue angle 1.8 1 0.99 8.09 31.37 37.89 23.95 7.58 a 3.6 1.03 8.00 31.65 38.77 25.47 6.82 bc 5.4 1.00 8.38 31.99 39.16 25.32 6.94 abc 1.8 2 1.03 8.41 32.87 39.45 25.93 6.78 bc 3.6 1.01 8.09 33.08 38.74 26.41 6.36 c 5.4 0.97 8.50 31.89 38.51 25.47 7.36 ab Significance ( P<0.05) NS NS NS NS NS Cultivar 'Strawberry Festival' 1.05 a 9.24 a 32.87 a 37.62 b 27.72 a 6.92 'Florida Radiance' 0.89 b 7.88 b 31.07 a 38.50 b 22.97 c 6.97 'Winter Dawn' 1.08 a 7.61 b 32.48 b 40.14 a 25.60 b 7.02 Significance ( P<0.05) * NS Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively.

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102 Table 416. Effects of irrigation volumes and frequencies on strawberry early and total yield. 200910 Season. Data examined with analysis of variance. Means followed by the same letter are not significantly different within a column. NS,* Not significant and significant at P<0.05 respectively. Irrigation Programs Early Yield Total Yield Volume Frequency (L/m/day) (cycles/day) (ton/ha) (ton/ha) 1.8 1 2.32 10.64 3.6 2.43 11.12 5.4 2.31 10.30 1.8 2 2.39 10.42 3.6 2.52 11.30 5.4 2.28 10.74 Significance ( P<0.05) NS NS Cultivars 'Strawberry Festival' 2.26 b 10.13 b 'Florida Radiance' 2.72 a 8.73 c 'Winter Dawn' 2.14 c 13.40 a Significance ( P<0.05)

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103 Figure 41. Effects of irrigation volumes and frequencies on soil water content (%). 200910 Strawberry Season.

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104 CHAPTER 5 SUMMARY AND CONCLUSI ONS The use of specific irrigation programs for the most planted UF cultivars may optimize strawberry production and water conservation in west central Florida. The proposed irrigation programs for these cultivars were tested during the strawberry seasons 200809 and 200910. The programs included irrigation volumes of 1.8, 3.6 and 5.4 L/m/day and two frequencies one and two cycles per day. The first strawberry season, the ear ly yield of Strawberry Festival was not affected by irrigation programs, it ranged between 7.8 and 9.0 t/ha. For total yields there were no effects when the irrigation programs were applied in a frequency of one cycle per day. However, when irrigation volumes were applied twice per day there was an effect on total yields. The lowest total yield was found in plots irrigated twice per day with 1.8 L/m/day, whereas the highest fruit yields were obtained in plots irrigated with either 3.6 or 5.4 L/m/day, rang ing between 29.6 and 30.0 t/ha. This result suggests that applying 3.6 L/m/day can be enough water to satisfy the strawberry water needs and the irrigation system requirements. Applying more water volume than 3.6 L/m/day can result in waste of water and nutrient leaching. Plant growth was affected at the end of the season by the irrigation frequency of two cycles per day, with higher water volume resulting in higher plant diameter. Shoot dry weight at the end of the season had a similar pattern, 5.4 L/m/day resulted in the highest shoot dry weight for both irrigation frequencies with a stronger effect when the water volume was applied in one cycle/day. Similar results were found by Kirnak et al. (2003) with higher shoot dry weight when the plants were irrigated with the higher volume evaluated. Both plant diameter and shoot dry weight had the lowest values

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105 when 1.8 L/m/day was applied in two cycles per day. That response was most likely because of the high evapotranspiration, air and soil temperature and solar irradiation in west central Florida at the end of the strawberry season (March and April 2009). Transpiration increases because there is a bigger plant canopy, as a result the crop water requirements increase and 1.8 L/m/day cannot cover those plant requirements. An irrigation volume of 3.6 L/m/day (average evapotranspiration in west central Florida) ca n supply the strawberry needs, this result is similar to what Gutal et al. (2005) found in strawberry irrigation when irrigating at alternate days 85% of t wo days pan evaporation gave higher yields and higher water use efficiency Nutritional status of the pla nts through the season was within the adequate ranges for the nutrients evaluated, N, P, K, Ca, Mg, S, Fe, Mn, Zn, B, and Cu. In terms of postharvest q uality, water volumes affected the strawberry fruit firmness at 14 WAT when the program was 1.8 L/m/day in one cycle per day. There was an effect of water volume applied in one cycle per day on t otal t itratable acidity; it was higher when the smallest water volume (1.8 L/m/day) was applied at the end of the season. This irrigation program had also the highest lightness among treatments. The irrigation programs (volumes and frequencies) had no effect on soluble solids content Contrary to the results of this of irrigation on fruit acidity but the total sugar content was lower in irrigated treatments for the cultivars evaluated. It was demonstrated that applying and irrigation volume of 5.4 L/m/day or mo re per season did not in crease strawberry yields, but did increase the water waste and leaching, while 1.8 L/m/day during the whole season result ed i n plant growth and total yield reduction. For Strawberry Festival an irrigation volume of 3.6

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106 L/m/day in one or two cycles per day result ed in higher total yields than 1.8 L/m/day, especially for the frequency of two cycles per day. Irrigation should occur only once per day when low water volumes are utilized. The irrigation volume of 1.8 L/m/day in one or tw o cycles per day can be use for Strawberry Festival at the beginning of the season (first 8 weeks) when plant size is still small and then the volume can be increased to 3.6 L/m/day when the size of the plants gets bigger and the water needs increase. T he second season the cultivars evaluated were Strawberry Festival, Florida Radiance and Winter Dawn. The weather conditions included low air and soil temperatures and low irradiation; there were fourteen days of temperatures below 0 C and approximately 24 days under freeze protection during the whole season, an unusual cold winter in west central Florida. For early and total yield there were no significant differences among the irrigation programs and there was no interaction between t he irrigation programs and the cultivars. For early yields the range was between 2.31 and 2.52 t/ha while the total yields ranged from 10.30 to 11.30 t/ha. There was a cultivar effect for both early and total yield. The highest early yield was obtained by Florida Radiance, followed by Strawberry Festival and Winter Dawn. Winter Dawn had the highest total yield of 13.40 t/ha for the season 200910. Strawberry Festival had a total yield of 10.13 t/ha and Florida Radiance had the lowest total yield, 8.73 t/ha. Plant growth variables such as plant diameter and chlorophyll content of the strawberry plants were not affected by the irrigation programs, there was not interaction irrigation program x cultivar but there were differences between cultivars. All nutrients were in adequate range through the season, W h itty et al (2002) mentioned that n utrient utilization and fertilization practices are influenced by the moisture status of the crop

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107 plants; There were effects of the irrigation program x cultivar for shoot dry weight. Strawberry Festival had the highest shoot dry weight from plots irrigated with 1.8 L/m/day in two cycles per day, while the lowest values were for Florida Radiance in all the irrigation programs. The soil water content was at field capacity the entire season, between 10% and 14%, even for the water volume of 1.8 L/m/day applied in one or two cycles per day. As a result the plants from all the plots had enough available water to supply crop water needs, since the temperatures were low the metabolic rate of those plants was probably not as high as the first season. The fact that Winter Dawn had the highest total yield might be related to the high dry root weight; these roots supported the cold weather and sustained the plant through the following months. Florida Radiance had the lowest root and shoot dry weight regardless of irrigation program and probably as a result of those values it had the lowest total yield. However, it had the highest early yield of 2.72 t/ha which represents more income for a strawberry grower than the early yields of Winter Dawn and Strawberry Festival. even the lowest water volume of 1.8 L/m/day allowed the soil to have an appropriate water status so the plant nutrients were available and leaching can be reduced. There were no significant differences among irrigation programs for root dry weight, ranging from 4.05 to 5.24 g, but there were differences among t he strawberry cultivars. Winter Dawn had the highest root dry weight followed by Strawberry Festival and Florida Radiance. There were no significant differences on total titratable acidity, soluble solids content and external color expressed as lightness, chroma and hue angle among irrigation programs in any of the prestorage evaluations. Kays (1999) mentioned that in

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108 horticultural crops, changes in water status can alter the general condition of the produce by decreasing quality and product weight. However, the strawberry fruit quality from all the irrigated plots was not affected by the wat er status, which meant that the lowest volume provide enough water without affecting the postharvest quality. There was no interaction irrigation program x cultivar but there were differences among cultivars. Win ter Dawn usually had the highest total tit ra table acidity and the lowest soluble solids content but it had higher chroma meaning a more vivid external color. The post storage analysis included total titratable acidity, soluble solids content external color (lightness, chroma and hue angle) and v isual quality. There were no significant differences among irrigation programs for any of the variables evaluated except for hue angle at 17 WAT and visual quality at the end of the season, where the lowest volume applied in one cycle/day had the highest f ruit visual quality inside the clamshell. Visual quality was different among cultivar only at 17 WAT, Winter Dawn had a slightly lower value than Strawberry Festival and Florida Radiance. According to Florida Automatic Weather Network (2010), average evapotranspiration during the 20092010 strawberry season (October 15, 2009 March 30, 2010) was 2.36 L/m/day; it was lower than the 2.54 L/m/day obtained in 20082009 strawberry season (October 15, 2008March 30, 2009). This difference might have influenced the result s during the second season. The Strawberry Festival plant diameters obtained the second season were much smaller than the ones obtained the first season, this small plant growth through the season had an impact on strawberry yield, and it is very likely that the other two cultivars had the same effect on growth.. Probably as a result of the low air and soil temperature, the low irradiation and the

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109 reduced transpiring surface area, the plants did not transpire as much as in a warmer season. In adittion to low evapotranspiration, the large amount of days that the plants were under freeze protection might also have reduced the growth rate. Other consequences of this weather conditions were hundreds of gallons of water spent in freeze protection. Satisfying crop water needs with as minimum leaching as possible is one of the goals of irrigation scheduling. The results of this research showed that every season performed different. In the first season irrigation programs had an influence on strawberry growth with larger plant diameter and shoot dry weight for the highest irrigation volume, higher marketable yield when a volume on 3.6 L/m/day was applied with much better results when the frequency of two cycles per day was used and postharvest qualit y including an increased on firmness as the water volume increased and higher total titratable acidity using the lowest volume of 1.8 L/m/day while the second season there was no influenced of the irrigation programs and it had more cultivar dependent results. In a strawberry season with weather conditions as the 200809 strawberry season a volume of 1.8 L/m/day can be used the first eight weeks and then the volume can be increased to 3.6 L/m/day to cover the water needs with better results when the frequency of two cycles per day is used. Reducing the irrigation volume from 5.4 L/m/day to the program described above strawberry growers could save around 11 million m3 of water per 24week season for the Florida strawberry industry as a whole without causing plant stress and yield reduction, excessive leaching, and saving energy for pumping.

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110 Based on the obtained results we can conclude that irrigation programs, and the interaction between irrigation programs and cultivars had an effect on strawberry growth, y ield and fruit quality in west central Florida, so the null hypotheses can be rejected. However, additional research needs to be conducted to confirm that irrigation volumes between 1.8 L/m/day and 3.6 L/m/day in one or two cycles per day can satisfy straw berry water requirements on sandy soils in west central Florida without reducing plant growth, marketable yield and postharvest quality

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111 APPENDIX TEMPERATURE DATA FROM FAWN WEATHER REPORT FOR BALM, FLORIDA DURING 2008 09 AND 200910 STRAWBERRY SEA SONS Table A 1. Daily average of data from FAWNDate weather report taken at 60 cm from soil from October 2008 to March 2009, Balm, FL. Season 2008 2009 Average Minimum Maximum ET0( o(L/m/day) C) 15 Oct 08 24.0 17.7 31.0 4.4 16 Oct 08 23.2 17.8 31.0 3.8 17 Oct 08 23.4 16.6 32.2 3.8 18 Oct 08 22.9 16.1 29.7 3.8 19 Oct 08 20.0 13.3 27.5 3.5 20 Oct 08 21.1 15.4 29.2 3.5 21 Oct 08 21.7 16.0 29.3 3.5 22 Oct 08 22.8 17.0 28.8 3.5 23 Oct 08 24.0 21.0 28.5 3.5 24 Oct 08 23.5 20.7 27.6 3.1 25 Oct 08 23.8 18.8 28.4 2.5 26 Oct 08 19.4 13.0 27.2 2.2 27 Oct 08 18.8 10.7 27.6 3.1 28 Oct 08 12.0 6.0 18.1 3.1 29 Oct 08 11.0 1.6 20.1 2.8 30 Oct 08 14.6 5.0 24.0 2.2 31 Oct 08 18.3 12.3 26.3 2.2 1 Nov 08 18.4 13.8 25.5 2.5 2 Nov 08 19.4 17.4 25.7 2.8 3 Nov 08 21.0 17.0 28.0 2.5 4 Nov 08 18.2 16.5 20.2 2.2 5 Nov 08 17.7 16.0 19.4 2.8 6 Nov 08 19.1 12.7 27.5 1.6 7 Nov 08 19.8 12.0 29.1 1.6 8 Nov 08 19.9 12.4 27.3 2.5 9 Nov 08 17.1 10.0 25.4 2.5 10 Nov 08 16.4 8.2 25.6 2.5 11 Nov 08 19.3 11.5 28.2 2.5 12 Nov 08 23.3 17.6 30.7 2.2

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112 Table A 1. Continued Date Season 2008 2009 Average Minimum Maximum ET0(* o(L/m/day) C) 13 Nov 08 25.1 20.6 31.9 2.5 14 Nov 08 24.5 19.7 32.2 2.8 15 Nov 08 22.7 17.9 27.6 3.1 16 Nov 08 12.4 3.2 17.9 2.8 17 Nov 08 11.0 2.6 20.3 2.2 18 Nov 08 13.3 6.8 21.9 1.9 19 Nov 08 9.4 2.2 18.6 1.6 20 Nov 08 10.9 0.8 21.4 1.9 21 Nov 08 14.1 6.1 23.8 1.6 22 Nov 08 11.8 4.5 21.2 1.6 23 Nov 08 13.9 7.4 23.2 1.9 24 Nov 08 16.1 9.6 25.6 1.9 25 Nov 08 15.0 7.8 23.9 1.9 26 Nov 08 12.4 2.8 23.0 1.9 27 Nov 08 11.1 0.6 23.4 1.9 28 Nov 08 13.4 3.3 26.3 1.6 29 Nov 08 17.3 6.4 27.4 1.6 30 Nov 08 18.6 15.2 25.2 1.9 1 Dec 08 16.5 11.9 20.6 2.2 2 Dec 08 11.7 2.1 17.0 1.9 3 Dec 08 11.0 1.3 21.7 1.9 4 Dec 08 16.2 8.8 26.0 1.3 5 Dec 08 16.7 8.1 26.5 1.6 6 Dec 08 17.2 9.3 24.4 1.9 7 Dec 08 14.2 6.2 19.9 1.9 8 Dec 08 13.4 3.0 24.5 1.9 9 Dec 08 19.3 10.3 28.1 1.6 10 Dec 08 22.5 18.8 29.4 1.6 11 Dec 08 19.9 16.5 22.3 2.2 12 Dec 08 14.4 8.2 18.3 2.2 13 Dec 08 11.7 3.0 20.4 1.6 14 Dec 08 17.8 10.9 25.5 1.6 15 Dec 08 20.2 17.8 25.1 1.3 16 Dec 08 19.9 13.6 27.4 1.9 17 Dec 08 20.5 14.6 27.6 1.6

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113 Table A 1. Continued Date Season 2008 2009 Average Minimum Maximum ET0(* o(L/m/day) C) 18 Dec 08 20.2 14.7 27.6 1.9 19 Dec 08 18.7 12.5 27.5 1.9 20 Dec 08 16.7 11.0 25.2 1.9 21 Dec 08 17.5 9.6 26.1 1.9 22 Dec 08 12.6 6.7 17.3 1.6 23 Dec 08 15.1 6.1 24.8 1.9 24 Dec 08 21.6 15.2 28.2 1.3 25 Dec 08 22.7 20.1 27.5 1.9 26 Dec 08 21.9 17.1 28.7 2.2 27 Dec 08 20.2 14.4 27.7 1.9 28 Dec 08 19.9 13.2 28.1 2.5 29 Dec 08 19.4 12.4 26.9 2.2 30 Dec 08 18.0 7.4 26.0 1.9 31 Dec 08 15.0 5.4 24.2 1.9 1 Jan 09 15.3 8.4 22.9 1.9 2 Jan 09 17.9 12.8 26.3 1.6 3 Jan 09 18.1 11.1 26.0 1.9 4 Jan 09 19.5 13.1 27.5 1.9 5 Jan 09 19.7 13.8 29.3 1.9 6 Jan 09 20.2 12.7 28.7 1.9 7 Jan 09 18.1 6.8 24.9 2.2 8 Jan 09 13.3 4.0 22.1 2.2 9 Jan 09 13.7 6.3 24.1 2.2 10 Jan 09 15.8 7.5 26.7 1.6 11 Jan 09 17.6 9.5 26.2 1.6 12 Jan 09 17.7 15.2 20.8 1.9 13 Jan 09 15.7 10.3 25.9 1.9 14 Jan 09 11.2 1.7 21.2 1.6 15 Jan 09 8.5 2.3 15.4 2.2 16 Jan 09 10.0 4.7 17.5 1.6 17 Jan 09 9.3 1.6 19.0 1.6 18 Jan 09 12.3 2.6 22.6 1.6 19 Jan 09 16.7 10.0 20.8 1.6 20 Jan 09 11.3 5.1 17.6 1.9 21 Jan 09 4.2 3.3 11.1 1.9

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114 Table A 1. Continued Date Season 2008 2009 Average Minimum Maximum ET0(* o(L/m/day) C) 22 Jan 09 5.5 4.7 18.1 1.9 23 Jan 09 9.8 2.1 23.0 1.3 24 Jan 09 12.7 2.4 22.7 1.6 25 Jan 09 15.5 5.6 26.3 1.9 26 Jan 09 18.2 9.0 27.5 1.9 27 Jan 09 20.2 13.2 28.2 2.2 28 Jan 09 21.4 16.8 28.6 2.5 29 Jan 09 21.0 16.7 27.1 2.5 30 Jan 09 14.1 8.8 18.8 2.8 31 Jan 09 8.9 1.7 17.6 2.5 1 Feb 09 11.8 1.4 21.3 1.9 2 Feb 09 16.0 11.8 19.4 1.9 3 Feb 09 12.2 3.0 15.8 2.2 4 Feb 09 7.4 1.1 13.6 1.9 5 Feb 09 3.8 2.7 12.6 2.2 6 Feb 09 8.7 1.4 20.3 1.9 7 Feb 09 12.7 4.6 22.6 1.9 8 Feb 09 14.8 6.7 24.4 2.2 9 Feb 09 15.5 5.4 25.4 2.5 10 Feb 09 17.5 9.0 27.6 2.8 11 Feb 09 20.3 11.9 29.2 2.8 12 Feb 09 20.4 16.6 26.8 3.1 13 Feb 09 19.9 12.8 29.8 3.5 14 Feb 09 17.3 9.8 24.9 2.8 15 Feb 09 20.2 15.8 26.7 3.5 16 Feb 09 18.4 8.9 24.3 3.1 17 Feb 09 14.1 5.6 24.1 2.8 18 Feb 09 17.0 7.5 24.9 3.1 19 Feb 09 18.1 15.1 24.3 3.1 20 Feb 09 12.5 3.2 18.7 3.5 21 Feb 09 12.0 0.2 24.5 2.5 22 Feb 09 16.3 7.7 24.7 2.8 23 Feb 09 15.4 8.7 23.6 2.8 24 Feb 09 14.5 5.0 24.8 2.8 25 Feb 09 17.0 9.9 25.6 3.1

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115 Table A 1. Continued Date Season 2008 2009 Average Minimum Maximum ET0(* o(L/m/day) C) 26 Feb 09 17.0 8.6 25.9 3.1 27 Feb 09 18.0 9.8 28.4 3.1 28 Feb 09 19.0 9.8 28.6 3.5 1 Mar 09 15.0 10.1 20.1 3.5 2 Mar 09 10.0 2.4 14.8 3.8 3 Mar 09 9.5 1.0 19.2 2.5 4 Mar 09 12.6 3.1 23.2 2.8 5 Mar 09 16.2 7.4 25.1 2.8 6 Mar 09 17.4 7.9 27.0 3.1 7 Mar 09 17.9 8.1 28.5 3.5 8 Mar 09 18.8 8.8 28.5 3.5 9 Mar 09 19.4 9.8 28.7 3.5 10 Mar 09 19.8 10.1 30.9 3.8 11 Mar 09 20.3 10.0 31.5 3.8 12 Mar 09 20.1 11.0 29.9 4.1 13 Mar 09 21.6 14.5 29.2 3.8 14 Mar 09 21.9 15.4 30.5 3.8 15 Mar 09 22.5 15.9 30.9 3.5 16 Mar 09 22.2 15.0 30.0 4.1 17 Mar 09 20.6 14.7 26.8 4.1 18 Mar 09 21.6 16.6 28.8 4.1 19 Mar 09 21.1 15.2 28.8 2.8 20 Mar 09 20.2 11.2 28.8 4.4 21 Mar 09 19.6 13.2 27.9 4.1 22 Mar 09 17.7 11.1 25.1 4.1 23 Mar 09 17.1 14.0 21.0 3.8 24 Mar 09 19.3 10.7 27.9 3.8 25 Mar 09 20.1 11.0 28.5 2.5 26 Mar 09 21.6 14.7 29.8 4.1 27 Mar 09 22.3 16.1 30.2 4.4 28 Mar 09 25.2 20.6 31.7 4.7 29 Mar 09 20.5 11.2 24.5 4.1 30 Mar 09 18.7 7.4 30.1 5.0 Daily averages of Penmanmethod Evapotranspiration. Florida Automated Weather Network

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116 Table A 2. Daily average of data from FAWNDate weather report taken at 60 cm from soil from October 2009 to March 2010, Balm, FL. Season 2009 2010 Average Minimum Maximum ET0(* o(L/m/day) C) 15 Oct 09 26.1 21.1 31.5 3.8 16 Oct 09 24.6 23.3 26.9 2.2 17 Oct 09 18.9 11.5 23.7 2.8 18 Oct 09 13.4 8.5 19.3 2.5 19 Oct 09 15.5 7.5 24.2 2.8 20 Oct 09 20.2 13.3 27.7 3.1 21 Oct 09 22.5 16.7 29.5 3.5 22 Oct 09 23.3 19.5 28.2 3.5 23 Oct 09 24.5 19.7 32.4 3.5 24 Oct 09 23.1 18.0 29.6 3.5 25 Oct 09 20.5 15.4 28.5 3.1 26 Oct 09 23.2 12.8 32.5 3.1 27 Oct 09 25.5 22.1 31.6 2.8 28 Oct 09 25.9 22.2 36.2 3.1 29 Oct 09 26.0 21.2 32.6 4.1 30 Oct 09 25.3 20.5 31.7 3.8 31 Oct 09 24.7 20.5 31.0 3.5 1 Nov 09 23.6 18.8 28.6 3.5 2 Nov 09 21.7 16.1 29.5 3.1 3 Nov 09 21.0 18.1 25.8 2.8 4 Nov 09 22.8 17.9 29.3 3.1 5 Nov 09 20.6 14.5 26.4 3.1 6 Nov 09 18.7 12.0 26.2 2.8 7 Nov 09 20.2 14.6 27.1 3.1 8 Nov 09 21.4 15.9 27.4 2.8 9 Nov 09 23.2 20.4 27.4 2.2 10 Nov 09 23.2 20.7 27.3 2.2 11 Nov 09 21.6 18.8 25.4 2.5 12 Nov 09 15.6 11.9 18.9 1.9 13 Nov 09 15.9 8.5 22.5 2.2 14 Nov 09 17.9 11.2 24.8 2.5 15 Nov 09 16.8 9.3 24.9 2.2 16 Nov 09 17.7 9.8 26.6 2.5 17 Nov 09 18.6 12.6 26.9 2.5

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117 Table A 2. Continued Date Season 2009 2010 Average Minimum Maximum ET0(* o(L/m/day) C) 18 Nov 09 20.0 12.4 28.3 2.5 19 Nov 09 19.3 14.1 25.9 2.5 20 Nov 09 18.6 13.0 26.1 2.2 21 Nov 09 20.7 15.8 27.7 2.5 22 Nov 09 22.2 18.4 26.9 2.2 23 Nov 09 21.9 17.8 28.2 2.5 24 Nov 09 21.4 17.7 27.0 2.2 25 Nov 09 19.3 16.7 20.3 1.3 26 Nov 09 16.3 8.0 21.0 1.9 27 Nov 09 10.8 5.0 17.9 1.6 28 Nov 09 10.7 4.6 18.6 1.6 29 Nov 09 14.7 5.8 24.5 1.9 30 Nov 09 16.9 8.4 25.5 1.9 1 Dec 09 20.0 14.0 27.5 2.2 2 Dec 09 22.7 17.7 28.0 2.5 3 Dec 09 20.4 15.9 24.0 1.9 4 Dec 09 14.2 12.8 16.4 1.3 5 Dec 09 13.6 8.3 16.5 1.6 6 Dec 09 11.9 4.9 19.5 1.6 7 Dec 09 19.5 14.5 24.6 1.9 8 Dec 09 21.5 18.7 26.4 2.2 9 Dec 09 23.5 18.7 28.3 2.5 10 Dec 09 19.6 14.7 24.7 1.9 11 Dec 09 14.0 11.5 17.5 1.6 12 Dec 09 20.3 14.0 25.8 1.9 13 Dec 09 21.9 16.2 29.0 2.2 14 Dec 09 21.8 16.6 29.0 2.2 15 Dec 09 22.0 16.0 29.4 2.2 16 Dec 09 19.7 15.7 25.6 1.9 17 Dec 09 18.9 15.3 22.7 1.9 18 Dec 09 20.0 16.4 22.7 1.6 19 Dec 09 14.8 12.0 18.3 1.6 20 Dec 09 10.8 5.4 16.0 1.3 21 Dec 09 8.5 1.5 16.7 1.3 22 Dec 09 10.2 3.3 18.7 1.6

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118 Table A 2. Continued Date Season 2009 2010 Average Minimum Maximum ET0(* o(L/m/day) C) 23 Dec 09 15.1 7.6 21.7 1.6 24 Dec 09 18.7 10.9 25.2 1.9 25 Dec 09 19.4 12.2 23.8 1.9 26 Dec 09 13.6 9.3 18.2 1.3 27 Dec 09 11.0 7.6 15.1 1.3 28 Dec 09 12.2 5.6 19.4 1.3 29 Dec 09 7.7 0.9 17.0 1.3 30 Dec 09 13.0 3.1 23.6 1.6 31 Dec 09 17.5 11.0 24.4 1.9 1 Jan 10 15.4 9.4 19.5 1.6 2 Jan 10 8.3 2.6 14.9 1.3 3 Jan 10 4.2 0.7 7.6 0.9 4 Jan 10 4.2 2.1 11.7 0.9 5 Jan 10 4.1 2.4 8.6 0.9 6 Jan 10 3.0 3.3 11.0 0.9 7 Jan 10 5.7 3.0 16.9 0.9 8 Jan 10 8.2 0.7 16.9 1.9 9 Jan 10 1.6 1.5 5.1 1.3 10 Jan 10 0.9 3.4 6.7 0.9 11 Jan 10 2.7 3.9 11.7 0.9 12 Jan 10 5.0 4.5 15.0 0.9 13 Jan 10 7.3 1.4 17.6 1.3 14 Jan 10 12.2 3.3 22.2 1.6 15 Jan 10 16.7 9.0 25.3 1.9 16 Jan 10 20.4 16.2 24.9 2.2 17 Jan 10 19.3 14.5 23.2 2.2 18 Jan 10 13.2 6.6 18.0 1.6 19 Jan 10 13.3 5.4 21.9 1.6 20 Jan 10 14.7 6.1 23.8 1.9 21 Jan 10 20.6 13.7 27.0 2.5 22 Jan 10 20.7 15.5 23.9 1.9 23 Jan 10 18.8 12.3 26.1 2.5 24 Jan 10 21.9 17.5 28.0 2.5 25 Jan 10 17.4 7.2 23.4 2.5 26 Jan 10 11.5 3.7 19.7 1.9

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119 Table A 2. Continued Date Season 2009 2010 Average Minimum Maximum ET0(* o(L/m/day) C) 27 Jan 10 11.2 3.8 20.4 1.9 28 Jan 10 13.8 5.5 23.4 2.2 29 Jan 10 16.4 9.6 24.2 2.2 30 Jan 10 18.5 13.9 24.8 2.2 31 Jan 10 12.3 8.7 15.3 1.9 1 Feb 10 14.0 9.0 17.6 1.9 2 Feb 10 16.9 12.1 21.3 1.9 3 Feb 10 12.8 8.7 19.1 2.2 4 Feb 10 16.8 9.6 25.0 2.8 5 Feb 10 19.3 16.0 24.9 2.2 6 Feb 10 15.2 11.1 18.4 2.2 7 Feb 10 10.1 4.4 13.7 1.9 8 Feb 10 9.9 2.7 19.2 2.2 9 Feb 10 15.4 8.3 21.5 2.2 10 Feb 10 10.2 5.2 15.2 2.5 11 Feb 10 7.7 2.0 14.7 1.9 12 Feb 10 9.3 7.1 11.7 1.3 13 Feb 10 7.6 1.5 12.0 1.9 14 Feb 10 7.2 0.1 16.4 2.2 15 Feb 10 11.1 0.3 21.6 2.8 16 Feb 10 9.6 3.2 12.7 2.2 17 Feb 10 8.3 1.5 13.6 2.2 18 Feb 10 8.0 0.8 14.5 2.2 19 Feb 10 10.9 2.9 18.2 2.2 20 Feb 10 14.2 7.8 22.4 2.8 21 Feb 10 16.4 6.9 26.1 3.1 22 Feb 10 19.1 13.1 25.4 2.8 23 Feb 10 19.9 14.0 25.9 3.1 24 Feb 10 14.6 10.3 22.2 2.2 25 Feb 10 8.4 1.8 13.6 2.5 26 Feb 10 7.4 0.6 17.1 2.5 27 Feb 10 7.6 0.9 13.4 1.9 28 Feb 10 10.4 1.9 16.9 2.8 1 Mar 10 11.1 0.5 21.9 2.8 2 Mar 10 14.9 7.1 21.4 2.8

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120 Table A 2. Continued Date Season 2009 2010 Average Minimum Maximum ET0(* o(L/m/day) C) 3 Mar 10 10.3 7.7 13.4 2.2 4 Mar 10 8.6 0.5 13.0 2.5 5 Mar 10 8.7 0.9 16.6 2.8 6 Mar 10 10.3 2.0 19.5 2.8 7 Mar 10 11.3 1.5 21.7 3.1 8 Mar 10 13.0 3.2 23.6 3.1 9 Mar 10 15.1 8.8 23.2 2.8 10 Mar 10 18.1 8.4 27.9 3.8 11 Mar 10 20.3 17.8 24.5 1.9 12 Mar 10 17.2 16.4 18.2 1.3 13 Mar 10 17.1 13.7 20.3 3.8 14 Mar 10 16.9 13.2 21.0 3.8 15 Mar 10 16.0 11.4 21.0 3.5 16 Mar 10 14.0 8.6 20.3 3.1 17 Mar 10 14.0 9.1 20.4 2.8 18 Mar 10 13.6 8.2 18.6 3.5 19 Mar 10 14.3 5.8 21.8 3.1 20 Mar 10 15.2 5.8 25.1 3.8 21 Mar 10 16.8 11.5 21.3 2.2 22 Mar 10 15.4 10.7 19.6 3.5 23 Mar 10 15.3 9.1 19.5 3.8 24 Mar 10 16.1 5.7 26.0 3.8 25 Mar 10 19.8 12.3 26.1 3.8 26 Mar 10 19.5 13.9 24.3 4.1 27 Mar 10 18.7 7.5 27.9 4.4 28 Mar 10 18.9 16.7 23.2 2.2 29 Mar 10 17.3 13.8 20.8 3.5 30 Mar 10 15.9 7.4 21.2 4.1 Daily averages of Penmanmethod Evapotranspiration. Florida Automated Weather Network

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121 LIST OF REFERENCES Albregts, E.E. and C.M. Howard. 1984. Strawberry production in Florida. University of Florida Institute of Food and Agricultural Sciences Bull. 841. Gainesville, FL. Allen, R., L. Pereira, D. Raes, and M. Smith. 1998. FAO irrigation and drainage paper no 56 crop evapotranspiration (guidelines for computing crop water requirements). Food and Agriculture Organization of the United Nations. Rome, Italy. August 2009. < http://www.fao.org/docrep/X0490E/X0490E00.htm > Azodanlou, R., C. Darbellay, J.L. Luisier, J.C. Villettaz, and R. Amado. 2003. Quality assessment of strawberries ( Fragaria species). J. Agric. Food Chem. 51: 715 721. Bhella, H.S. and W.F. Kwolek. 1984. The effects of trickle irrigation and plastic mulch on zucchini. HortScience 19:410411. Blatt, C.R. 1984. Irrigation, mulch, and double row planting related to fruit size and yield of Bounty strawberry. HortScience 19:826827. Chandler, C.K. 2009. Plant patent application publication No. US 2009/0013438 P1. Chandler, CK., B.M. Santos, N.A. Peres, C. Jouquand, A. Plotto, and C.A. Sims. 2009. Florida Radiance Strawberry. HortScience 44:17691770. Chandler, C.K., M. Herrington, and A. Slade. 2003. Effect of harvest date on soluble so lids and titratable acidity in fruit of strawberry grown in a winter, annual hill production system. Acta Hort. 626:353354. Chandler, C.K., D.E. Legard, D.D. Dunigan, T.E. Crocker, and C.A. Sims. 2000. Strawberry Festival strawberry. HortScience 35:1366 1367. Chandler, C.K. and D.C. Ferree. 1990. Response of Raritan and Surecrop strawberry plants to drought stress. Fruit Var. J. 44:183185. Clark, G.A. and A.G. Smajstrla. 1996. Design Considerations for Vegetable Crop Drip Irrigation Systems. Hort T echnology 6: 155159. Clark, G.A., C.D. Stanley, and F.S. Zazueta. 1993. Qualitative sensing of water movement from a point source emitter on a sandy soil. Appl. Eng. Agr. 9:299303. Clothier, B., D. Scotter, and E. Harper. 1985. Threedimensional infilt ration and trickle irrigation. Trans. Am. Soc. Agric. Eng. 28:497 501. Darnell, R.L. 2003. Strawberry Growth and Development. In: The Strawberry: a book for growers others N. Childers (ed.). Institute of Food and Agricultural Sciences, Horticultural Sci ences Department, Uni versity of Florida, Gainesville, FL.

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122 Del Pozo Insfran, D., C.E. Duncan, K.C. Yu, S.T. Talcott, and C.K. Chandler. 2006. Polyphenolics, Ascorbic Acid, and Soluble Solids Concentrations of Strawberry Cultivars and Selections Grown in a Winter Annual Hill Production System. J. Amer. Soc. Hort. Sci. 131:8996. Dving, A. and F. Mge. 2002. Methods of testing strawberry fruit firmness. Acta Agriculturae Scandinavica Section B Soil and Plant Sci 52:4351. Durner, E.F. and E.B. Poling. 1987. Flower Bud Induction, Initiation, differentiation and development in the Earliglow Strawberry. Sci Hort 31:61 69. Dwyer, L.M., D.W. Stewart, L. Houwing, and D. Balchin. 1987. Response of strawberries to irrigation scheduling. HortScience 22:42 44. El Farhan, A.H. and M.P. Pritts. 1997. Water requirements and water stress in strawberry. Adv. Strawberry Re.16:512. Ells, J.E., E.G. Kruse, and A.E. McSay. 1989. Scheduling irrigation for cucumbers. HortScience 24:448452. Elrashidi, M.A., M .D. Mays, S.D. Peaslee, and D.G. Hooper. 2004. A technique to estimate nitrate nitrogen loss by runoff and leaching for agricultural land, Lancaster County, Nebraska. Commun. Soil Sci. Plant Analysis 35:25932615. Fernandez, G.E., L.M. Butler, and F.J. Lo uws. 2001. Strawberry growth and development in an annual plasticulture system. HorScience 36:12191223. Finkl, C.W. and R.H. Charlier. 2003. Sustainability of subtropical coastal zones in southeastern Florida: Challenges for urbanized coastal environments threatened by development, pollution, water supply, and storm hazards. J. Coastal Res. 19:934943. Fl. Aut. Weather Netw. 2010. Database. May 2010. < http://fawn.ifas.ufl.edu/data/>. Francis, F.J. 1998. Color Analysis. In: Food Analysis. 2nd Edition. S.S. Nielsen (ed.). Aspen Publishers, M D Golden, E.A., J.R. Duval, E.E. Albregts, and C.M Howard. 2003. Intermittent sprinkler irrigation for establishment of bare root strawberry transplants. July 2009. < http://edis.ifas.ufl.edu/HS192 >. Guimer, J., O. Marf, L. Candela, and L. Serrano. 1995. Nitrate leaching and strawberry production under drip irrigation management. Agr. Ecosystems and Environ. 56:121135.

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123 Gun nes, P., O. Kravchuk, S.M. Nottingham, B.R. DArcy, and M.J. Gidley. 2009. Sensory analysis of individual strawberry fruit and comparison with instrumental analysis. Postharvest Biol.Technol. 52:164172. Gutal G.B., V.N. Barai T.A Mane, J.K. Purkar, and N.L. Bote 2005. Scheduling of irrigation for strawberry through drip. J. Maharashtra agric. Univ. 30:214215. Haman, D.Z. and A.G. Smajstrla. 2005. Scheduling tips for drip irrigation of vegetables. July 2009. < http://edis.ifas.ufl.edu/AE092 >. Haman, D.Z. and F.T. Izuno. 2003. Soil plant water relationships. July 2009. < http://edis.ifas.ufl.edu/AE021 >. Hancock, J. 1999. Strawberries. CAB Intl., N Y Hardeman, T.L., H.G. Taber, and D.F. Cox. 1999. Trickle irrigation of vegetables: water conservation without yield reduction. J. Vegetable Crop Production 5:2333. Heintz, C.M. and A.A. Kader. 1983. Procedures for the sensory evaluation of horticultural crops. Hort Science 18:1822. Hoberg, E., D.Ulrich, E. Krger, and E. Schpplein. 2002. Effect of irrigation on strawberry flavor quality. Acta Hort. 567:735738. Hochmuth, G.J. 2003. Progress in mineral nutrition and nutrient management for vegetable crops in the l ast 25 years. HortScience 38:9991003. Hoppula, K.I. and T.J. Salo. 2007. Tensiometer based irrigation scheduling in perennial strawberry cultivation. Irrig. Sci. 25:401409. Hsiao, T.C. 1990. Plant atmosphere interactions, evapotranspiration, and irrigation scheduling. Acta Hort. 27 8 :55 66. Jouquand, C., C.K. Chandler, A. Plotto, and K. Goodner. 2008. A sensory and chemical analysis of fresh strawberries over harvest dates and seasons reveals factors that affect eating quality. J. Amer. Soc. Hort. Sci. 133:859867. Kader, A.A. 2002. Postharvest biology and technology: an overview. In: Postharvest Technology of Horticultural Crops. 3rd Edition. A.A. Kader (ed.). UC Publication 3311. University of California, Division of Agriculture and Natural Resources, Oakland, CA Kader, A.A. 2002. Quality and safety factors: evaluation for fresh horticultural crops. In: Postharvest Technology of Horticultural Crops. 3rd Edition. A.A. Kader (ed.). UC Publication 3311. University of California, Division of Agriculture and Natural Resources, Oakland, CA

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124 characteristics of strawberry genotypes at different maturation states. Food Chem. 100:12291236. Kaspar, T.C. and W.L. Bland.1992. Soil temperature and root growth. Soil Sci. 154:290299. Kays, S.J. 1997. Postharvest physiology of perishable plant pr oducts. Exon Press, Athens, GA. Kays, S.J. 1999. Preharvest factors affecting appearance. Postharvest Biol.and Technol.15: 233 247. Kirda, C., P. Moutonnet, C. Hera, and D.R. Nielsen. 1999. Crop yield response to deficit irrigation Kluwer Academic Publishers, The Netherlands. Kirnak, H., C. Haya, D. Higgs, I. Bolat, M. Simsek, and A. Ikinci. 2003. Effects of preharvest dripirrigation on strawberry yield, quality and growth. Aust. J. Exp. Sci. 43:105111. Kirnak, H., C. Kaya, D. Higgs, and S. Gercek. 2001. A long term experiment to study the role of mulches in the physiology and macronutrition of strawberry grown under water stress. Aust. J. A gric. Res. 52:937943. Kirschbaum, D.S., M. Correa, A.M. Brquez, K.D. Larson, and T.M. DeJong. 2004. Water requirement and water use efficiency of fresh and waiting bed strawberry plants. Acta Hort. 664:347350. Krger, E., G. Schmidt, and U. Brckner. 1999. Scheduling strawberry irrigation based upon tensiometer measurement and a climatic water balance model. Scientia Hort. 81:409424. Lamont, W.J. 1993. Plastic mulches for the production of vegetable crops. HortTechnology 3:3539. Lamont, W.J. 2005. Plastics: modifying the microclimate for the production of vegetable crops. HortTechnology 15:477481. Andersen. 2007. Water relations and yield of lysimeter grown strawberr ies under limited irrigation. Scientia Hort.111:128132. Locascio, S.J. 2005. Management of irrigation for vegetables: Past, present, and future. HortTechnology 15:482485.

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125 Macias Rodriguez, L., E. Quero, and M.G. Lopez. 2002. Carbohydrate differences in strawberry crowns and fruit (Fragaria x ananassa) during plant development. J. Agric. Food. Chem. 50:33173321. Martnez, D.E. and J.J. Guiamet. 2004. Distortion of the SPAD 502 chlorophyll meter readings by changes in irradiance and leaf water status. Agronomie 24:4146. McGuire, R.G. 1992. Reporting of objective color measurements. HortScience 27: 12541255. McNeal, B.L., C.D Stanley, W.D. Graham, P.R. Gilreath, D. Downey, and J.F. Creighton. 1995. Nutrient loss trends for vegetable and citrus fields in west central Florida: I. Nitrate. J. Environ. Qual. 24:95 100. Mnager, I., M. Jost, and C. Aubert. 2004. Changes in phytochemical characteristics and volatile constituents of strawberry (cv Cigaline) during maturation. J. Agrc. Food. Chem. 52:12481254. Meyers, K.J., C.B. Watkins, M.P. Pritts, and R. Hai Liu. 2003. Antioxidant and antiproliferative activities of strawber ries. J. Agric. Food. Chem. 51: 68876892. Michigan State University Extension. 2004. Critical spring temperatures for tree fruit and small fruit bud stages. April 2010. < http://web1 .msue.msu.edu/vanburen/crtmptxt.htm >. Mitcham, E.J. and F.G. Mitchell. 2002. Postharvest handling systems: small fruits. In: Postharvest Technology of Horticultural Crops. 3rd Edition. A.A. Kader (ed.). UC Publication 3311. University of California, Divis ion of Agriculture and Natural Resources, Oakland, CA Mitchell, F.G., E. Mitcham, J.F. Thompson, and N. Welch. 1996. Handling strawberries for fresh market. 2442, Division of Agriculture and Natural Resources, University of California Oakland, CA. Nunes, M.C.N., J.K. Brecht, A.M.M.B. Morais, and S.A. Sargent. 1995. Physical and chemical quality characteristics of strawberries after storage are reduced by a short delay to cooling. Postharvest Biol.Technol. 6:1728. 003. The effect of drip irrigation on the yield and content of organic compounds in fruits of three strawberry cultiv ars. Folia Hort 15: 159 166. Peres, N.A., J.F. Price, W.M. Stall, C.K. Chandler, S.M. Olson, T.G Taylor, S.A. Smith, E.H. Simonne, and B.M. Santos. 2009. Strawberry production in Florida. In: Vegetable production handbook for Florida, 20092010. S.M. Olson and E.H. Simonne (eds.). Ins t. Food Agr. Sci. Publ., University of Florida.

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126 Perkins Veazie, P. 1995. Growth and ripening of strawberry fruit. Hort. Rev. 17:267297. Phene, C.J. and O.W. Beale. 1976. Highfrequency irrigation for water nutrient management in humid regions. Soil Sci Soc. Am. J. 40:430 436. Prange, R. K. and J. R. DeEll. 1997. Preharvest factors affecting postharvest quality of berry crops. HortScience 32 :824 830. Rolbiecki, S., R. Rolbiecki, C. Rzekanowski, and M. Derkacz. 2004. Effect of different irrigation regi mes on growth and yield of Elsanta strawberries planted on loose sandy soil. Acta Hort. 646:163166. Sadler, G.D. and P.A. Murphy. 1998. pH and titratable acidity. In: Food Analysis. 2nd Edition. S.S. Nielsen (ed.). Aspen Publishers, M D Santos, B.M., and C. K. Chandler. 2009. Influence of nitrogen fertilization rates on the performance of strawberry cultivars. Intl. J. of Fruit Sci. 9:126135. Sav, R., J. Peuelas, O. Marf, and L. Serrano. 1993. Changes in leaf osmotic and elastic properties and canopy structure of strawberries under mild water stress. HortScience 28:925927. Serrano, L., X. Carbonell, R. Sav, O. Marf, and J. Peuelos. 1992. Effects of irrigation regimes on the yield and water use of strawberry. Irr. Sci.13:4548. Shin, Y., R. J.A. Ryu, R. H. Liu, J.F. Nock, and C.B. Watkins. 2008. Harvest maturity, storage temperature and relative humidity affect fruit quality, antioxidant contents and activity, and inhibition of cell proliferation of strawberry fruit. Postharvest Biol. Technol. 49: 201 209. Shokaeva, D.B. 2008. Injuries induced in different genotypes by winter freeze and their effect on subsequent yield. Plant Breeding 127:197202. Simonne, E.H. and G.J. Hochmuth. 2010. Soil and fertilizer management for vegetable production in Florida. In: Vegetable production handbook for Florida, 20102011. S.M. Olson and B.M. Santos (eds.). Inst. Food Agr. Sci. Publ., University of Florida. Simonne, E.H. and M.D. Dukes. 2009. Principles and practices of irrigation management for vegetabl es. In: Vegetable production handbook for Florida, 20092010. S.M. Olson and E.H. Simonne (eds.). Inst. Food Agr. Sci. Publ., University of Florida. Simonne, E.H., D. Studstill, and R.C. Hochmuth. 2006. Understanding water movement in mulched beds on sandy soils: an approach to ecologically sound fertigation in vegetable production. Acta Hort. 700:173178.

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127 Simonne, E.H., D.W. Studtill, R.C. Hochmuth, J.T. Jones, and C.W. Starling. 2005. On Farm Demonstration of Soil Water Movement in Vegetables Grown with Plasticulture July 200 9 < http://edis.ifas.ufl.edu/HS251 >. Simonne, E., D. Studstill., B. Hochmuth, T. Olczyk, M. Dukes, R. Munoz Carpena, and Y. Li. 2003. Drip irrigation: The BMP era An integrated approach to water and fertilizer management for vegetables grown with plasticulture. July 2009. < http://edis.ifas.ufl.edu/HS172 > Smajstrla, A.G., F.S. Zazueta, and D.Z. Haman. 2002. Potential Impacts of Improper Irrigation System Design. July 2009. < http://edis.ifas.ufl.edu/AE027 >. Southwest Florida Water Management District. 2010. Water Conservation, Water 101. Introduction. May 2010. < http://www.swfwmd.state.fl.us/conservation/water101/intro.html > Tomlinson, R., R. Weldon, M. Woods, S. Thornsbury, and A. Wysocki. 2004. Florida and the Fresh Strawberry Industr y. J. Food Distrib. Res. 35:197 198. U.S. Department of Agriculture. 2010. Vegetables 2009 summary May 2010. < http://usda.mannlib.cornell.edu/usda/current/VegeSumm/VegeSumm 0127 2010.pdf >. Wang, S.Y. and M.J. Camp. 2000. Temperatures after bloom affect plant growth and fruit quality of strawberry. Sci. Hort. 85:183199. Whitty, E.B., D.L. Wright, and C.G. Ch ambliss. 2002. Water use and irrigation management of agronomic crops. July 2009. < http://edis.ifas.ufl.edu/AA131 >.

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128 BIOGRAPHICAL SKETCH Maricruz was born in San Jose, Costa Rica. She grew up surrounded by farms and developed a strong interest for fruit production. She pursued a Bachelor of Science in Plant Sciences at the University of Costa Rica and graduated from it in 2005, after that she continued with advances studies in Plant Science and graduated from it in 2007. From July 2005 to May 2008 she worked as a research assistant at the Postharvest Technology Laboratory of the University of Costa Rica as a c oordinator of the evaluations of liquid 1MCP Technology (AgroFresh Inc. PA .) in tropical fruits. Since August 2008 she was a masters student and worked in Dr. Bielinski Santos horticultural program at the Gulf Coast Research and Education Center (Balm, FL), a unit in the Institute of Food and Agricultural Sciences (IFAS) at the University of Florida